SUMMARY OF CURRENT RESEARCHES 



RELATING TO 



ZOOLOGY AND BOTANY 



(principally invertebrata and cryptogamia), 



MICROSCOPY, Etc.* 



ZOOLOGY. 



VEKTEBRATA. 

 a. Erabryology.f 



Influence of Temperature on Development of Fowl's Egg-.} — C. L. 

 Edwards has made a careful study of this question. His data are based 

 on 238 incubated and 59 unincubated eggs. 



The physiological zero, or the temperature below which there is no 

 development, is given by most authors at 28° ; it is established at the 

 degree included between 20° and 21°. The index of development 

 between 20° and 30° "75 is given; the normal average diameter of the 

 blastoderm and of the area pellucida is calculated. The average volume 

 of the egg is also considered. We cannot summarise the tables, but 

 the general result shows a direct dependence of ontogenetic organisation 

 upon warmth. 



Retrogressive Changes in Ovarian Follicles. § — A. Buhler first 

 describes the retrogressive changes in the burst follicle of Cyclostomes 

 (lamprey) and Teleosts. There is an almost complete degeneration, 

 well seen in Coregonus ; the epithelium and the theca connective-tissue 

 degenerate pari passu and almost equally. At the beginning of the 

 process in Coregonus there is in the theca a certain progressiveness in 

 the formation of a few large connective-tissue cells, and this is much 

 more marked in the lamprey, where the theca holds out till after the 

 degeneration of the epithelium. The residue of the theca becomes an 

 inseparable part of the connective-tissue of the superficial ovarian 

 lamina. There is no formation of new tissue, — no corpus luteum. 



Buhler then discusses the degeneration of the unburst follicle. This 

 is more complex since it involves the absorption of the ovum, partly 



* The Society are uot intended to be denoted by the editorial " we," and they do 

 not hold themselves responsible for the views of the authors of the papers noted, 

 nor for any claim to novelty or otherwise made by them. The object of this part of 

 the Journal is to present a summary of the papers as actually published, and to 

 describe and illustrate Instruments, Apparatus, &c, which are either new or have 

 not been previously described in this country. 



t This section includes not only papers relating to Embryology properly so called, 

 but nlso those dealing with Evolution, Development, Reproduction, and allied subjects. 



% Amer. Journ. Physiol., vi. (1902) pp. 351-97. 



§ Morphol. Jahrb., xxx. (1902) pp. 377-452 (2 pis. and 2 figs.). 



