18G SUMMARY OF CURRENT RESEARCHES RELATING TO 



SUMMAEY 



OF CURRENT RESEARCHES RELATING TO 



ZOOLOGY AND BOTANY 



(principally Tnvertebrata and Cryptogamia), 



MICROSCOPY, &c, 



INCLUDING ORIGINAl COMMUNICATIONS FROM FELLOWS AND OTHERS.* 



ZOOLOGY. 



A. VERTEBRATA:— Embryology, Histology, and General. 



a. Embryology-t 



Polar Globule of Mammalian Ovum.} — Prof. G. Bellonci describes 

 the formation of a polar globule iu the ovarian ova of several mammals 

 — mole, guinea-pig, and rabbit. His best results were obtained from 

 the two former. What he observed in the rabbit ovum was less satis- 

 factory. He notes and figures the pos : tion of the germinal vesicle at 

 the animal pole, the transformation of the nucleus, the spindle, the 

 equatorial aggregation, in one good instance the formation of two well- 

 formed " coronse," and the actual separation. In the formed polar 

 globule he was never able to demonstrate a morphologically complete 

 nucleus. He discusses the question of the really cellular nature of 

 these extruded elements, and compares what he has observed in 

 mammals with other cases of karyokinesis. In an appended paper he 

 discusses certain curious phenomena of segmentation in the ovarian ova 

 of mole aud rabbit, which suggest the beginning of parthenogenesis, but 

 are more probably interpreted as phenomena of degeneration. 



Vestiges of Zonary Decidua in Mouse. §— Mr. J. A. Ryder, with 

 the assistance of Mr. G. Fetterolf, has investigated the decidua of the 

 mouse. The mucosa thickens very much around the embryo, forming a 

 rin« of tissue around the blastodeimic vesicle. Of this, only that por- 

 tion persists which lies near where the discoidal placenta is subsequently 

 formed. On the side opposite the placenta, and at the sides of the 

 blastodermic vesicle, the ring is absorbed. " The hoop-like thickening 

 which is continued from opposite sides of the placental region, and 

 which encircles the foetus and its membranes, is nothing more or less 

 than the transitory representative of a zonary or girdle-like decidua.'' 

 The hypertrophied portion or annular band of the mucosa is absorbed 



* The Society are not 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 also those dealing with Evolution, Development, and Reproduction, and allied 

 subjects. X Mem. Accad. Sei. Bologna, vi. (1^86) pp. 3U3-5, 367-9 (1 pi.). 



§ Amer. Natural., xxi. (1887) pp. 1037-8. 



