摘要:

The formation of cysts in the sebaceous glands and follicle ends that occurs in "rhino" mice can be suppressed by massive vitamin A therapy. The significance of this finding is discussed in relation to the mode of action of the rhino gene.

ISSN:1923-4287    

DOI:10.1139/cjr49d-014

出版商:NRC Research Press    

年代:1949

数据来源: NRC

摘要:

When freshly laidDrosophilaeggs were placed in a graded series of P32concentrations in the culture media, death of treated individuals occurred most frequently at the end of the larval period and in the pupal stages. No adults emerged from cultures having an initial concentration of 0.65 rutherford (rd.) or higher per ml. food. The calculated concentration of P32expected to reduce emergence of adults to 50% is 0.120 rd. per ml. A dosage of 1.30 rd. per ml. prevents transformation of larvae to pupae. Three out of 132 X-chromosomes from males reared in medium having an initial concentration of 0.0325 rd. per ml. carried new recessive lethal "genes".

ISSN:1923-4287    

DOI:10.1139/cjr49d-015

出版商:NRC Research Press    

年代:1949

数据来源: NRC

摘要:

The proventricular region ofTetraopes tetraophthalmusForst. is relatively poorly developed, consisting merely of the posterior end of the stomodaeum, which tapers toward the mid-gut and is invaginated into the anterior end of the mid-gut to form the oesophageal valve. It is of the type found in inactive insects that feed on plants and in which the crop is small.

ISSN:1923-4287    

DOI:10.1139/cjr49d-016

出版商:NRC Research Press    

年代:1949

数据来源: NRC

摘要:

The ribonucleic acid, desoxyribonucleic acid, and the ratio of ribonucleic acid to desoxyribonucleic acid in the liver of immature pullets treated with 4.5 mgm. testosterone propionate over a 12-day period were all increased when this treatment was supplemented by treatment with estrogen. The possible significance of these effects in relation to other effects of similar gonadal hormone treatments is discussed.

ISSN:1923-4287    

DOI:10.1139/cjr49d-017

出版商:NRC Research Press    

年代:1949

数据来源: NRC

摘要:

On July 1, 1948, 100 millicuries of radioactive phosphorus, P32, was added to the surface of an acid bog lake of area 0.3 hectares (0.8 ac.) and depth 6 m., situated near Halifax, Nova Scotia. The lake had a well developed⁁ zone of cold, stagnant water at the bottom with a thermocline above. Within a few hours the P32was taken up strongly by the sphagnum (which made up most of the lake margin), by the floating plankton, and by sponges. Within a few days it had reached the bodies of fishes (FundulusandNotemigonus), and within a fortnight had accumulated in their skeletons and viscera. No appreciable uptake of P32by such bottom rooted forms as the cranberry (Vaccinium) and leather leaf (Chamaedaphne) was observed for more than two weeks. Penetration of added phosphorus into the lake depths was very slow, and even at the end of eight weeks the material was only doubtfully detected at the bottom. There was no evidence of active uptake by bottom mud. The ratios of maximum count per wet weight of organism to maximum count for the same quantity of lake water were as follows:Zooplankton40,000Fundulus13,000Sponge 4500Sphagnum 400Vaccinium300Blue-green alga 300Chamaedaphne100Nuphar

ISSN:1923-4287    

DOI:10.1139/cjr49d-018

出版商:NRC Research Press    

年代:1949

数据来源: NRC

摘要:

By feeding a hen repeated daily doses of sodium dihydrogen phosphate of equal P32activity, eggs with high and nearly uniform P32content were obtained for use in hatching experiments. Eleven eggs were incubated. The embryos and chicks that died during or after incubation were dissected and analyzed for total and specific activities in the various fractions. Two of the chicks, both females, are still living. They are being raised so that observations may be made on their ability to reproduce and the effect of the radioactivity, if any, on their offspring.

ISSN:1923-4287    

DOI:10.1139/cjr49d-019

出版商:NRC Research Press    

年代:1949

数据来源: NRC

摘要:

The embryological development of three species of grasshoppers is described in gross aspect by means of a key that relates morphological development to the duration of incubation at 25 °C. The three species are so similar that they are treated as one. The rate of development and stage of entering diapause are compared with those ofM.differentialis.

ISSN:1923-4287    

DOI:10.1139/cjr49d-020

出版商:NRC Research Press    

年代:1949

数据来源: NRC

摘要:

Eggs ofMelanoplus bivittatus(Say) possess a special water-absorbing area, the hydropyle, similar in function to that ofM.differentialis(Thos.). The extent of hydration was measured as eggs ofM.bivittatusdeveloped at 25 °C. on contact moisture. The total amount of water absorbed amounts to about 60% of the original weight of the egg. Absorption is negligible for the first four days, is maximal on the eighth and ninth days, and later may exhibit a second period of minor increase and decline, which varies in time of occurrence. About 88% of the total absorption occurs during anatrepsis. Eggs denied contact moisture from the time of oviposition develop to the end of anatrepsis and remain viable for long periods, provided desiccation is not severe. When contact moisture is provided, such eggs hydrate very rapidly and continue development with a retardation of two or three days. Extra moisture from the environment is essential for the revolution and katatrepsis of the embryo.

ISSN:1923-4287    

DOI:10.1139/cjr49d-021

出版商:NRC Research Press    

年代:1949

数据来源: NRC