( 487 ) 

 SUMMARY 



OF CUEEENT EESEABCHES EELATING TO 



ZOOLOaY AND BOTANY 



{principally Tnvertehrata and Cryptogamia), 



MICROSCOPY, &c., 



INCLUDING ORIGINAL COiDIUNICATIONS FROM FELLOWS AND OTHERS* 



ZOOLOGY. 



A. GENERAL, including Embryology and Histology 

 of tlie Vertebrata. 



Early Stages of the Guinea-pig Ovum.t — Graf F. Spee has 

 published the results of his observations on this subject. Up to the 

 beginning or middle of the fourth day, the ova remain in the oviduct, 

 whence they must be carefully extracted. Eggs of two days have four 

 segmentation spheres, around and between which a coagulated mass 

 soon appears pos^ mortem. On the third day the limits of the cells are 

 unrecognizable ; but they may be more or less isolated by bursting the 

 ovum. After the fifth day, the coagulum no longer appears around 

 the segmentation-spheres. In all the early stages jpost mortem changes 

 are very great and rapid. While still free, after the fourth day, the 

 ova lie in the tip of the uterus, whence they may be driven by forcing 

 with a syringe a current of warm 0*5 per cent, salt solution into the 

 vagina, and out of the tip of the uterus (after cutting off the oviduct). 

 By employing this method, Spee has obtained germ-vesicles agreeing 

 essentially with corresponding stages as found in other mammalia, 

 the principal difference being that the cells are relatively larger, 

 segmentation not having progressed so far. There is an outer wall 

 close against the zona pellucida, and composed of a single layer of 

 cells, spindle-shaped when seen in section, polygonal when viewed 

 from the surface. At one pole is an accumulation of cells, the 

 Keimhiigel, while at the opposite pole the cells at the outer layer 

 are thickened. In a later stage the cells of the latter pole are found 

 to have thrown out branching processes which penetrate the zona 

 pellucida. Apparently these processes increase in size; and it is 



* The Society are not to be considered responsible for the views of the 

 authors of tlie papers referred to, nor for the manner in which those views 

 may be expressed, the maiu object of this part of the Journal being to present a 

 summary of the papers as actually published, so as to provide the Fellows with 

 a guide to the additions made from time to time to the Library. Objections and 

 coriections should therefore, for the niost part, be addressed to tue authors. 

 (The Society are not intended to be denoted by the editorial " we.") 



t Arch. f. Anat. u. Physiol., Anat. Abth., 1883, pp. 44-60 (,1 pl-)- Cf 

 Science, i. (1883) pp. 406-7. 



