710 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
SUMMARY 
OF CURRENT RESEARCHES RELATING TO 
ZOOLOGY AND BOTANY 
( 'principally Invertebrata and Crypto garni a), 
MICROSCOPY, &c., 
INCLUDING ORIGINAL COMMUNICATIONS FROM FELLOWS AND OTHERS * 
ZOOLOGY. 
A. VERTEBRATA Embryology, Histology, and General. 
a. Embryology, f 
Maturation of the Egg-Cell of the Fowl.J — Prof. M. Holl, after 
describing young ova, and the formation of the tunica adventitia and 
the follicle, gives an account of the changes which occur in the nucleus 
during the process of maturation. In its youngest form the nucleus 
is circular or shortly oval, and placed in the middle of the egg. It 
soon becomes round if it was oval, and moves nearer to the surface of 
the cell. As it increases in size it returns to the centre of the cell. 
It shortly afterwards becomes flattened on one side, and with this again 
passes to the surface of the cell. During these changes in position the 
nucleus is always increasing in size. 
The nuclear membrane has at first a distinct double contour, but 
this is lost as the nucleus grows ; the membrane in time becomes 
almost or altogether lost, and the nuclear contents abut on the elements 
of the yolk. The nucleolus is, in the early stages of the nucleus, 
always visible in 2 • 5 p sections ; it is always placed peripherally in 
a space of the chromatic plexus. After increasing somewhat in size, 
the nucleolus begins to break up, and finally disappears altogether. 
The nuclear substance appears at first as an extremely fine plexiform 
mass, which does not stain ; it fills up the narrow spaces of the nuclear 
plexus and extends in a thin layer between it and the nuclear 
membrane. This layer soon increases so that it forms an ever widen- 
ing zone around the spherical plexus. In cross-section the whole of 
the nuclear substance appears as a disc, in the interior of which is 
* 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 aHied 
subjects. % SB. K. Akad. Wiss. Wien, xcix. (1890) pp. 311-70 (1 pi.). 
