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The changing temperature requirements of Chesias legatella Schiffermuller during embryonic development are investigated. The eggs are laid in the autumn and embryogenesis is interrupted by a short diapause at the germ band stage, after which development proceeds slowly throughout the winter. The effects of temperature during the pre-diapause, diapause and post-diapause phases of development are assessed by examination of the rate and variability of morphogenesis through all the embryonic stages. An examination is presented of the effect of temperature during the late autumn on the rate and uniformity of diapause termination, and consequently on the length of the hatching period the following spring.

The embryonic development of Dysdercus fasciatus Sign. is described in terms of 15 arbitrary stages based on external morphological characters. The effects of treating eggs early in development with juvenile hormone and a mimic (JH) are then described in terms of the stages at which embryonic development is arrested and the resulting morphological aberrations are summarised. The effects of the treatment of two strains of D. fasciatus with two JH (Law's mimic and Ayerst synthetic juvenile hormone) are described and compared in terms of both the hatchability of the eggs and the stage distributions of the arrested embryos. Law's mimic was more effective than Ayerst SJH in preventing egg hatch, and the Malawi strain was less susceptible than the Reading strain. Embryonic development was never arrested earlier than the commencement of blastokinesis (Stage VIII). After treatment with Ayerst SJH most embryos of both strains were arrested during dorsal closure (Stages XI-XII) or at the time of eclosion (Stages XHI-XIV). Treatment of the Reading strain with Law's mimic resulted in the majority of embryos being arrested during blastokinesis (Stages VIII-X) at all doses. Examination of the timetable of development in both control and treated eggs reveals a dramatic reduction in developmental rate in treated eggs at the commencement of blastokinesis. It is suggested that JH may act on eggs of D. fasciatus in three ways: interference with eclosion, differentiation and the embryonic movements during blastokinesis.

SUMMARY Fourteen cultivars of north temperate, Australian, Mexican and Rhodesian origins, were grown in eight treatments: 2-day-lengths (10 h and 14h) × two temperature regimes (18/13 °C and 25/20 °C) × two seed vernalization treatments (unvernalized and 28 days at 1–2 °C). Numbers of days to 50 % ear emergence, leaf numbers and spikelet numbers of the main shoots were recorded. The north temperate cultivars were the most sensitive to daylength: in long days their mean spikelet number was 15 and they headed in 40–50 days, while in short days they had a mean of 24 spikelets and failed to head in 100 days. The Rhodesian cultivars were the least sensitive, but nevertheless headed 20–30 days earlier and had three to five fewer spikelets per ear in long days. The effects of vernalization on the tropical cultivars were related to maturity class: they ranged from negligible in early cultivars such as Sonora 64 and Devuli to decreases of 20 days to heading and seven spikelets in late cultivars such as Mexico 120 and Cajeme 71 in long days. The effects of temperature varied with cultivar and with vernalization treatment. Early cultivars and vernalized late cultivars headed earlier and had fewer spikelets in the warmer regimes while unvernalized late cultivars tended to have more spikelets and headed later. It is suggested that some vernalization of these late cultivars took place in the cooler regime. The significance of the results for the understanding of the physiological basis of the adaptation of wheat cultivars to different climatic zones is discussed.

The embryonic development of Chesias legatella Schiffermiiller and C. rufata Fabricius is described and compared. Eggs of C. rufata develop in approximately nine days at 20°C; those of C. legatella overwinter and hatch after five or six months. The morphology of the developing embryo is described in detail and is essentially similar in both species except during the formation and early development of the germ band. Morphogenesis is divided into a number of arbitrary stages and the relative duration of the different stages is compared in these and other species.

We refer the reader to the IHES notes of Zeeman (14) for basic facts aboutPL(or piecewise-linear) manifolds. IfMmis a locally flatPL-submanifold ofQm+2, our object will be to study the normal structure ofMinQ: one of our main results is:There exists a PL-bundle over M, with fibre a 2-simplex, which is PL-homeomorphic to a neighbourhood of M in Q; moreover, the bundle and homeomorphism are unique up to equivalence. We also make an application to smoothing theory.

Some of the more recent studies into the compressive and tensile strengths of small human bone samples are discussed. The scatter of results is compared to that for tests on cement which, like bone, is a composite material. A list of factors which may influence the result of strength tests on bone is given and discussed. It is suggested that by careful consideration of these factors and by standardization of the variables among them, the scatter of results could be reduced.

1. The following results are special cases of theorems of Irwin and Zeeman, respectively (see (4), (9), (10)).(a) Let V be a (2n − m + 1)−connected piecewise-linear m−manifold (bounded or not), where m − n ≥ 3. Then any element of πn(V) can be represented by a piecewise-linear imbedding of Sn in V.(b) Let M be a (2n − m + l)-connected closed piecewise-linear (m − 1)-manifold, where m − n ≥ 3. Then two piecewise linear imbeddings of Sn−1 in V are isotopic if and only if they are homotopic.

The following problem arose in recent work of Stewart Robertson on finite subsets of Eucidean space admitting transitive groups of isometries (1): Determine the greatest number of involutions that can be possessed by a finite group of given ordern.

The object of this paper is two-fold: first to collect together the known facts about combinatorial cobordism in general, and then to calculate the groups for the first 8 dimensions. As in (29), we shall denote the unoriented and oriented cobordism groups in dimensionnbyand Ωn, and will distinguish the combinatorial from the differential case by affixesc, d.

Summary 1.This paper is based on the report of a case in which pyloric stenosis without esophageal stricture developed approximately one month after the ingestion of 45 cc. of hydrochloric acid. 2.The ingestion of caustic alkalis produces damage primarily to the esophagus; pyloric stenosis develops only occasionally (20%), whereas, the ingestion of corrosive acids produces its primary effect on the stomach. This may result in perforation of the stomach and death. If the patient recovers from the acute gastritis, he often develops a severe pyloric obstruction and achlorhydria in from four to six weeks. Approximately 20% of the patients with pyloric stenosis also develop esophageal stricture. 3.The pyloric stenosis may be so severe as to result in death unless corrected surgically. 4.The clinical picture produced by pyloric stenosis following acid ingestion may closely simulate gastric malignancy.

Tensile strength and density measurements were carried out on small samples of cortical bone taken from the lateral quadrant of the central region of the femoral diaphysis. A graph of strength against density shows that density is not the sole factor in determining bone strength, although there is a general trend of increasing strength with increasing density. Other factors must be taken into account to explain variation in bone strength.