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The manubrium of a primarily non-terminal ephyra is formed from the connecting tube between two ephyra rudiments. The proboscis of the polyp remaining arises in a manner similar to that of the manubrium of the non-terminal ephyra. The apical opening of an ephyra normally closes before liberation. The connecting strands are covered with endoderm. The longitudinal muscles of a polyp may be hollow and the cavities are not in communication with the peristomial pits. The formation of the peristomial pit is associated with the development of the manubrium. The gastral filaments are formed as paired outgrowths of the endoderm of the columella. They do not involve the longitudinal muscle in their production. They originate early in the history of an ephyra. There are definite currents over the ectoderm caused by flagellated ectoderm cells. The segments of a strobila may give rise to ephyrae or polyps and the oral disc may separate unchanged to continue its existence as a polyp.

This study of the development of a rhynchonellid brachiopod has revealed marked differences from that of Terebratella inconspicua (Percival, 1944). These principally concern the origin of the mesoderm and of the lophophore. The origin of theright and left mesoblastic sacs in Tegulorhynchia and in Terebratella depends on the stage at which the blastoporal groove exerts its influence, earlier in the former, leading directly to their formation, later in the latter, leading indirectly to their formation. The subsequent division into anterior and posterior sacs is similar in both genera. The lophophore of Tegulorhynchia is the product of the anterior lobe, and considerable centripetal movement occurs during the sinking of the centre from which the brachial fold (or buccal lip) is derived. The process of formation of the lophophore in Terebratella can be regarded as a much shortened version of that which occurs in Tegulorhynchia. In the latter genus the origin of the brachial fold is elaborate and protracted, while in the former the brachial fold does not appear until 8 pairs of cirri have been formed.

WE now communicate some preliminary results of the investigation on methylated agar prepared from the acetate previously described in NATURE1. By the simultaneous deacetylation and methylation of acetylated agar in chloroform; CH3CO = 38.5 per cent), an apparently homogeneous methylated agar was obtained 78° in chloroform; OCH3= 31 per cent), the methoxyl content of which remained constant despite repeated methylations.

A STUDY of the development of the rhynchonellid, Tegulorhynchia nigricans, Sowerby, shows the larva to be furnished with two pairs of large tufts of long setæ set on the hind margin of the mantle rudiment. The members of one pair lie dorso-laterally, those of the other pair laterally. On the mid-ventral surface of the larval mantle is a longitudinal thickening of ciliated cells some 70 µ long and reaching to the hind edge. Two bands of muscle fibres pass forward inside the larval pedicle and are finally inserted one each side of the mid-dorsal line of the base of the mantle.

Barry and Dillon1reported the isolation from the red seaweed Rhodymenia palmata of a polysaccharide which gave D-xylose on hydrolysis. Our special interest in xylans2has led us to investigate this substance more fully as part of the research programme of the Scottish Seaweed Research Association. Since work on this subject has also been continued in University College, Galway, we have agreed with Prof. T. Dillon to publish a preliminary account of our findings.

IN view of the recent publication by N. W. Pirie1on the acetolysis of agar, it seems advisable to communicate preliminary results from this laboratory, where an investigation on the structure of agar has been proceeding.

THE term ‘algic cellulose’ was applied by Stanford1to an insoluble residue obtained from seaweeds after the removal of algin, and many workers have assumed that this material is identical with the cellulose of land plants. Although denied by some2, this view has been supported by Kylin3on the evidence of the colour reaction with iodine and sulphuric acid, and by Russell-Wells4, who also demonstrated the solubility of the material in cuprammonium hydroxide and prepared an acetate.

THROUGH the kindness of Dr. A. P. Orr of the Marine Station, Millport, in supplying a quantity of Gigartina stellata which is used in the preparation of ‘British Agar’1, we have been able to investigate a polysaccharide isolated from this material.

IN 1942, through the kindness of Dr. A. P. Orr of the Marine Station, Millport, specimens of agars of known history were examined to see if evidence could be secured for the formulation of Jones and Peat1, which demands a relatively high sulphur content (S, 1.8 per cent; that is, SO4, 5.4 per cent).

FOR some time we have been studying the mucilaginous polysaccharides of carrageen moss, and it now seems desirable, in view of the recent letter by Dillon and O'Colla1, to communicate some of our results.

ALTHOUGH it is now well established1,2,3that the alkaline hydrolysis of suitably substituted hexoses carrying sulphate groups on either the 3 or 6 positions readily yields 3 : 6 anhydrohexose derivatives, all our attempts to obtain evidence for the formation of ethylene oxide rings have been, until recently, unsuccessful, in marked contrast to the behaviour of the toluene-p-sulphonates4. It is now evident that this has been due largely to the fact that the barium salts of the sugar ethereal sulphates investigated were insoluble in organic solvents and the hydrolyses had, in consequence, to be carried out in aqueous media. Under such conditions experimental difficulties arise, for any ethylene oxide derivatives which may have been formed would be hydrolysed with accompanying Walden inversions4. Thus since the ethylene oxide ring formation would also involve a Walden inversion on the carbon atom where the sulphate group was originally attached, the production in recognizable quantity of a derivative of a hexose different from that in the original starting material depends on the relative ease of fission of the two ethylene oxide ring linkages. Thus the hydrolysis of a derivative of glucofuranose-3-sulphate could yield a 2 : 3 anhydro-allofuranose, which might give either a gluco- or an altrofuranose derivative, or both3.

WE have now confirmed the accuracy of the structure (I) cooH.co.co.CHOH.CHOH.CH2OH which we had previously assigned to the first (reversible) oxidation product of ascorbic acid on the ground that it yields oxalic acid and trihydroxybutyric acid (l–threonic acid) on further oxidation1. The above formulation represents an open chain acid, but it is now evident that at the moment of formation the substance behaves as a lactone of (I) and not as the free acid. We have already advanced a constitutional formula for ascorbic acid (represented by (II) and its tautomerides) which shows the relationship between (I) and (II) to be as follows :2

THE introduction of cross-linkages into soluble synthetic linear high polymers is followed by a decrease in solubility. In Nature, an interesting parallel appears to be afforded on one hand by the water-soluble polysaccharide lichenin, which consists ofan unbranched β-glucopyranose chain (C6H10O5)nwhere n = 80–1601, 2and by cellulose on the other, if for the latter the structure of β-glucopyranose chains (or multi-membered loops) linked at intervals by cross-linkages3be accepted. This communication contributes to the question of the structural difference between lichenin and cellulose.

DR. CARPENTER has kindly allowed us to examine specimens which were undoubtedly mature Planaria albissima, Vejd. On comparing these with drawings of immature specimens taken near Leeds in May and October 1922 and March 1923, and Pately Bridge, we feel convinced that the specimens from Yorkshire belong to this species. So far we have failed to find examples in which the sexual organs are developed.