SUMMARY OF CURRENT RESEARCHES 



RELATING TO 



ZOOLOGY AND BOTANY 



(PRINCIPALLY INVERTEBRATA AND CRYPTOGAMIA), 



MICROSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 

 a. Embryology. + 



Ovarian Eggs of Guinea-pig.! — L. Loeb discusses very fully a 

 number of points relating to the ovarian egg, such as the oocytes of the 

 medullary strands (Markstrange) of the ovary, follicle atresia, and the 

 progressive changes in the eggs. He found that in 10 p.c. of the 

 ovaries of guinea-pigs of less than six months, follicle-like bodies with 

 Plasmodia and syncytia were present. Other cells near the centre of the 

 follicles had a cylindrical or cubical form. Of ninety-eight ovaries, 

 mostly older, only one possessed such a follicle-like body. They are 

 probably unruptured follicles in atresia. In the neighbourhood of these 

 formations similar alterations of ovarian tissue are traceable in different 

 directions ; they appear to be in the course of the blood and lymph 

 vessels. Various transformations of these bodies are described ; they 

 finally degenerate, and are destroyed by the ingrowth of connective 

 tissue. Oocytes in all stages of development were found in the " medullary 

 canals" of the ovary of the young guinea-pig. They never show 

 progressive alterations, and do not reach the size of the matured egg, 

 but degenerate early and leave behind them an often thickened mem- 

 brana pellucida. The canal may alter cystically, and the cysts may 

 reach a considerable size. In the ovary mitoses may occur in segmented 

 egg-cells, and two contemporaneous mitoses may be found in two distinct 

 segments. The author looks upon this as the beginning of a partheno- 

 genetic development which soon comes to an end. Various mechanical 

 and chemical stimuli failed to induce progressive alterations in the 

 ovarian egg. 



* The Society are not intended to be denoted !>y 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, etc., 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 also those dealing with Evolution, Development, Reproduction, and allied subjects, 



J Arch. Mikr. Anat., lxv. (1905) pp. 728-53 (1 pi.). 



