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Instances of differentiation in absence of an inductor have multiplied to such extent that the classical picture of embryonic induction is in process of serious re-examination (Grobstein & Parker, 1958; Nieukoop, 1955; Trinkaus & Groves, 1955). Questioned on the basis of the occurrence of neural differentiation without organizer in explants of presumptive epidermis (Barth, 1941; Holtfreter, 1947, 1955; Ito, 1952), the necessity for a specific inductor has proved difficult to demonstrate in other inductive systems. Grobstein & Parker (1958) have shown that tubule formation in metanephrogenic mesenchyme may occur in abnormal sites in vivo without contact with its normal ureteric inductor and even in the anterior chamber of the eye without contact with any other tissue. Niu (1958b) has recently reported a certain percentage of neural differentiation in explants of presumptive epidermis cultured as controls in his salt medium without addition of inductor substances.

1. Presumptive epidermis of stage 11 gastrula differentiates into epithelial sheets with ciliated patches.2. Alteration of the basic salt solution by addition of calcium chloride or magnesium sulfate or sodium bicarbonate results in the differentiation of nerve cells.3. Calcium chloride, magnesium sulfate, sodium bicarbonate, ammonium sulfate and lithium chloride will induce nerve cells from presumptive epidermis when applied for a few hours beginning with stage 11.4. Lithium chloride applied to the presumptive epidermis for varying lengths of time induces various cell types.5. Lithium chloride applied in various concentrations to the presumptive epidermis induces various cell types.6. A concept of sequential induction is introduced as a formal explanation of the lithium chloride inductions.

Delay lines have been shown to offer many advantages for multi-wire proportional chamber readout, particularly in applications involving single event counting. It is desirable to optimize the delay line with respect to cost, mechanical convenience, linearity, and risetime. We have constructed several types of tapped delay lines and have tested them with a 20 × 20 cm proportional chamber. A delay line constructed of 100 1 meter lengths of RG-316/U miniature coaxial cable offers excellent linearity (< .2%), a rise time of 30 nsec, and total delay of 500 nsec. Printed circuit delay lines, with characteristics similar to the coaxial lines were constructed, and offer greatly improved packaging properties at a cost of less than $ 1 per wire.

1. The process of induction after sucrose treatment is accompanied by an increased uptake of Na22 as compared with the uptake by untreated controls.2. The process of induction by lithium chloride treatment results in an increased uptake of Na22 during the lithium treatment.3. The process of induction after lithium treatment is accompanied by an increased uptake of Na22 as compared with untreated controls.

Six types of commercial sets are considered: 1. A 2 k.w., Quenched or Rotary Synchronous Spark, Ship Set; 2. A 0.5 k.w., Quenched or Rotary Synchronous Spark, Ship Set; 3. A 0.25 k.w., Rotary Non-Synchronous Spark, Cargo Ship Set; 4. A 3 k.w., Rotary Non-Synchronous Spark, Land Station Set; 5. A 2 k.w., Quenched Spark, Gasoline engine driven, Land Set; 6. A 10 k.w., Quenched Spark Land Set for Juneau, Alaska. Photographs and descriptions of these are given, with special reference to nature of traffic, power source, space limitations, and expense.

When frogs are exposed during early cleavage to low concentrations of the sulphydryl inhibitor, p-chloromercuribenzoic acid, cleavage is inhibited at the animal pole, while the marginal zone and yolk cleave normally. Eggs exposed before first cleavage cleave only at the animal pole, while blastulae and gastrulae are inhibited uniformly in all regions by the sulphydryl reagent. The selective inhibition of animal-pole cells by p-chloromercuribenzoic acid is not readily explained on the basis of regional permeability differences or variations in sensitivity of the surface coat to inhibitors, since exposure of eggs to iodoacetamide results in normal cleavage at the animal pole, together with inhibition of cleavage at the marginal zone and in the yolk. The inhibition produced by p-chloromercuribenzoic acid is mediated by sulphydryl groups, since the effects of the inhibitor are reversible by thioglycollate and cysteine. When various protein fractions are extracted from eggs or hatched embryos and tested for sulphydryl groups by means of the nitroprusside reaction, the soluble fractions are found to contain freely reactive sulphydryl groups, while the yolk proteins are entirely lacking in reactive protein-bound sulphydryl groups. When the yolk proteins are fractionated into phosphoprotein (S2) and non-phosphoprotein (Si), the latter alone is found to contain masked SH groups that become fully reactive only after denaturation plus reduction of disulphide groups. It is suggested that the protein-bound SH groups at the marginal zone are protected against p-chloromercuribenzoic acid inhibition by a high content of soluble thiols such as reduced glutathione, which are synthesized at the expense of sulphur-containing amino acids from the yolk protein Si, under the control of enzymes and nucleotides such as adenosine triphosphate present in the dorsal lip region and marginal zone.

SummaryProtein extracts of the neural plate plus underlying chordamesoderm induce the presumptive epidermis of the gastrula to form neural tubes. However no differences were obtained in the structure of the neural tubes which were induced by extracts of anterior as compared with posterior regions of the neural plate and underlying chordamesoderm. Preparations of the anterior and posterior regions of the neural plate and underlying chordamesoderm which were killed by freezing and subsequent drying induced neural tubes in the explanted presumptive epidermis of the gastrula. Quantitative differences in the frequency of induction were obtained with the posterior neural plate and underlying chordamesoderm inducing with the greatest frequency.

1. A method has been devised for studying the regression of the zooid of Perophora into a stolon and the subsequent differentiation of a new zooid from this stolon. 2. Circulatory cells of the stolon resulting from regression will aggregate into masses larger than the minimal size necessary for differentiation of a zooid, but fail to differentiate into a zooid. 3. The cells of a zooid after staining with neutral red appear in the stolon during regression and finally come to lie in the newly formed zooid. 4. During the cycle of adult zooid to stolon to newly formed zooid, there is no evidence for cell division from studies with tritiated thymidine. 5. It is concluded that under conditions of starvation, an adult zooid furnishes all the cells for the formation of a stolon and the subsequent zooids without cell division.

A study of the effects of a series of monovalent cations, Li + , Na + and K + , and a series of divalent cations, Mn 2+ , Ca 2+ and Mg 2+ , upon small aggregates of cells taken from the presumptive epidermis of Rana pipiens gastrulae revealed that these ions induce nerve and pigment cells (Barth, 1965). The effectiveness of both series of ions as inductors was similar to their effects on decreasing the electrophoretic mobility of DNA as determined by Ross & Scruggs (1964). When it was found that sucrose in glass-distilled water also would induce nerve and pigment cells the role of ions as inductors came under closer scrutiny. A study of the nature of the induction by sucrose revealed that a relatively high concentration of sodium ions was necessary in the culture medium used after sucrose treatment (Barth, 1966). If after sucrose treatment the cells were cultured in a medium containing a relatively low concentration of NaCl no induction occurred, and the cells differentiated into ciliated and mucus cells, as did untreated controls. One suggestion offered was that sucrose altered the cell surface and sodium ions penetrated and brought about the actual induction. In any case the dependence of the induction by sucrose upon sodium ions brought into question the nature of the induction by other substances such as LiCl. Does LiCl induce by itself or does it merely change the cell surface so that sodium ions can enter and effect the actual induction? In the experiments recorded below small aggregates of presumptive epidermis cells were treated for varying lengths of time with LiCl and then returned to relatively high and low concentrations of NaCl in our standard culture medium. A second question arises regarding the period of competence for induction of nerve and pigment cells. If the induction actually occurs after the LiCl is removed, then the competent period must be extended farther than revealed by the LiCl treatment.

erfullt ist, ist die durch (1) gegebene Beziehung zwischen wy und ^-gegen laufig. Die Wachstumsrate des Sozialprodukts ist ceteris paribus um so groser (kleiner), je niedriger (hoher) die Lohnquote ist. Will man also, so folgt daraus, eine hohere Wachstumsrate erreichen, mus man die Lohnbezieher nur dazu bewegen, einer Verringerung der Lohnquote zuzustimmen. Soweit man eine Steigerung der Wachstumsrate nicht als reinen Selbstzweck ansieht, erhebt sich jedoch die Frage: cui bono? Bringt es den Lohnempfangern einen Vorteil, wenn sie sich zu einer Senkung ihres Anteils am Volkseinkommen bereit finden, d.h. wird die ihnen zufallende Lohn summe groser sein, wenn sie einer Senkung der Lohnquote zugunsten eines schnelleren Wachstums des Volkseinkommens zustimmen?

1. A sequence of inductions has been obtained with a single inductor applied to the presumptive epidermis in various concentrations and for varying lengths of time.2. A neural inductor, such as magnesium sulfate or calcium chloride, will induce a part of the sequence such that a subminimal exposure to lithium chloride then is able to induce pigment cells.3. After lithium chloride is used to induce pigment cells, a strong neural inductor such as sodium bicarbonate, magnesium sulfate or calcium chloride applied immediately after lithium treatment may reverse the induction and nerve cell differentiation will result.4. The sequence of inductions is a necessary one, as evidenced by the fact that at the peak of competence for pigment cell induction, lithium chloride first induces nerve cells and then pigment cells.

Exhaust emission control systems employing air injection and exhaust manifold reactors in place of conventional exhaust manifolds have been developed to control vehicle emissions to 0·25 gram (20 p.p.m.) of hydrocarbons and 5·0 grams (0·22 per cent) of carbon monoxide per mile. These low emission levels have been achieved with good driveability, good vehicle performance and very little loss in fuel economy. Durability tests of a number of exhaust manifold reactor systems indicate that acceptable life in consumer service can be attained. Non-nickel alloy steels developed by specialty steel manufacturers, and based on the iron-chromium- aluminium system, appear to be useful materials of construction for reactors. These alloys coupled with the now demonstrated simplifications in reactor design offer one route to lower ultimate costs of these units. The commercial development and application of exhaust manifold reactor systems seems entirely feasible.

Taut and tight manifolds, introduced recently by H. Wu, are characterized as follows. Let D D denote the open unit disk in C C . The complex manifold N N is taut iff the set A ( D , N ) A(D,N) of holomorphic maps from D D into N N is a normal family. If d d is a metric inducing the topology on N , ( N , d ) N,(N,d) is tight iff A ( D , N ) A(D,N) is equicontinuous. It is also shown that every taut manifold is tight in a suitable metric.

The Kobayashi pseudodistance on a connected complex space is continuous with respect to the standard topology. IC this pseudodistance is an actual distance, it induces the standard topology. Let X be a connected (reduced) complex space. The Kobayashi pseudodistance dx(p, q) between points p and q of X is defined as follows ([6, p. 462], [7, pp. 97-98]). Let p denote the distance defined by the PoincareBergman metric on the open unit disk D in the complex plane. Choose points P PO,PloP' . Pk-1 pk=q of X, points a1,, * * , ak, bl, * * *, bk of D, and holomorphic maps fl, *, *fk from D into X such that fj(aj)= Pj-l and fj(bj)=pj for j= 1, , k. Then dx(p, q) is defined to be the infimum of the numbers p(a,, bl)+... + p(ak, bk) taken over all such finite chains joining p and q. Clearly dx is a pseudodistance on X. In case dx is an actual distance we will show that it induces the standard topology, i.e., the topology underlying the given complex structure on X. Several authors have tacitly used this fact; cf. [1, Proposition 3.8, pp. 68-69], [4, Proposition 1, pp. 50-51], [5, Theorems 2 and 3, pp. 590-591], [6, Theorem 3.4, pp. 465-466], [8, Theorem 1, pp. 11-12]. The only published proof, however, seems to be the one given by H. L. Royden [9, Theorem 2, pp. 133-134] for complex manifolds. Our proof uses only three elementary facts about the Kobayashi pseudodistance: if f: Y--Z is a holomorphic map, it is distance decreasing in the sense that dz(f(p),f (q))

Small aggregates of cells prepared from explants of ventral ectoderm of Rana pipiens gastrula were treated for 3-4 hrs in 71 mM Li+ added to standard solution. When cultured in standard xsolution containing 1.3 mM K+, the aggregates of ventral ectoderm cells differentiated into nerve and pigment cells. As the K+ concentration in the culture medium was raised through 2.3, 3.3 and 5.3 mM, the frequency of pigment cells declined and networks of vacuolated cells were formed, which later fused to form small notochordal masses. Raising the K+ to 7.3 and 9.3 mM gave nerve and pigment cells again, as in the lower potassium concentrations. The effect of high K+ on lithium-induced cells becomes irreversible during the first 18 hrs. Cells may be returned to 1.3 mM K+ after 18 hrs and notochord differentiation will occur.Induced notochord cells first appear as somewhat larger cells which become filled with very small vacuoles by 7-8 days of culture. These small vacuoles then coalesce to form larger and larger vacuole...

It is reported on results and experiences with immunofluorescent technique in dermatological diagnostic, using FITC-conjugated anti-human IgG "Berlin-Weissensee". While immunofluorescene on our conditions is an important diagnostic help in systemic and discoid lupus erythematosus as well as bullous pemphigoid, there are many nonspecific results in patients suffering from pemphigus vulgaris.

Cell aggregates prepared from ectoderm of the Rana pipiens gastrula are induced to differentiate into nerve and pigment cells by brief treatment with sucrose or lithium. The induction is dependent upon the concentration of Na + in the medium into which treated cells are transferred. Induction follows transfer into standard solution with 88 m M (high) Na + but does not occur in 44 m M (low) Na + in standard solution. Induction may be rendered independent of high Na + if Ca 2+ and/or Mg 2+ are added to the inducing solution and the treatment period is extended. Cells treated with 170 m M sucrose in glass-distilled water plus 0.74 m M Ca 2+ for 6 hr form pigment cells when cultured in 44 m M Na + . Cells treated with 170 m M sucrose substituted for Na + in standard solution containing all ions other than Na + become independent of Na + after 8 hr and form pigment cells in 44 m M Na + as well as in 88 m M Na + . Tris HCl can substitute for Na + in standard solution for the post-induction period up to 15 hr, and nerve and pigment cells develop in 44 m M Na + . A general theory is advanced to relate ion regulation of induction during normal gastrulation to the present data.

A highly simplified atomic absorption procedure for the determination of stable strontium in fluid milk, milk powder, and alfalfa is evaluated. A comparison is made between the atomic absorption method of additions and the standard curve method. A suggested stepwise procedure is given. (GRA)

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SummaryResults of cellulose digestibility in a series of studies utilizing calcium and phosphorus depleted suspensions of rumen microorganisms confirm the calcium requirements of rumen microorganisms, and indicate phytin phosphorus utilization to be significantly more sensitive than inorganic phosphorus to calcium levels and ratios. Data suggest decreased phytin phosphorus utilization at the wider Ca/P ratios to be more directly related to a chemical effect than to enzyme inhibition, and provide basic evidence of the critical need for careful consideration of levels as well as ratios in the adjustment of calcium to phosphorus ratios for ruminant animals on high phytin rations.

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