ZOOLOGY AND BOTANY, MICROSCOPY, ETC, 
71 
By pressing on the first two blastomeres, Reinke made them longer 
than broad, and displaced the nuclei to one side. In these cases a 
radiate system appeared in the half of the blastomere which was free 
from the nucleus. This system was centered in a space free from fibrils, 
disappeared as the nucleus passed into the resting state, reappeared with 
the next mito is, and was quite independent of the centrosomes. 
On ova preserved by Hermann’s mixture, vom Rath’s mixtures, 
and best by corrosive-glacial acetic acid or corrosive-glacial acetic acid 
and bichromate of potash, Reinke made some important observations. 
An apparent honeycombed structure is demonstrably due to the dis- 
position of yolk-granules. The sphere around the sperm-nucleus shows 
at least hints of a centrosome or of several, afterwards more distinct. 
Reinke refuses to allow that Fol’s statements as to a “ quadrille ” 
have been disproved by the criticisms of Wilson and Boveri. 
The sphere of the sperm-nucleus divides into two, and the female 
pro-nucleus is received between them ; spindle mantle and central sp : ndle 
are differentiated ; the granular, apparently honeycomb-like structure of 
the plasma becomes modified into rays, except in a neutral zone which 
is the subsequent plane of division. Details of this “ internal division ” 
of the plasma are given. 
But soon the whole peripheral part of the radiate plasmic ball re- 
assumes the honeycomb structure. Only around the spheres do the rays 
persist. They end peripherally in the honeycomb-like plasma, centrally 
in the margin of the sphere. In the network of the spheres there are 
1—2 dozen centrosomes, grouped to form a microcenti um. 
The peripheral plasma begins again to change into rays, which are 
continued to the membrane of the egg ; the hitherto spherical “sphere” 
becomes like a biconvex lens ; the microcenti um becomes like a plate ; the 
sphere passes into a peculiar pear-like shape ; cell-division and sphere- 
division ensue. 
The changeable shape of the sphere is the result of the outer shape 
of the cells and of the radiate structure of the cell-substance. Reinke 
confirms Heidenhain’s theory of cellular mechanics. 
A Study of Auricularia.* — Prof. C. Chun describes Auricularia 
nudibranchiata , the larva of some undetermined Holothurian. He dis- 
cusses the form of the body and the course of the ciliated band ; the 
single layer of flat epithelium which seems to represent the larval ecto- 
derm, and does not degenerate as Semon affirms; the bilateral nervous 
system ; the complicated mouth region and its ciliated band. The 
unusually luxuriant development of the oral and aboral bands raises the 
question of their physiological import, and Chun points out that in 
addition to their locomotor function, they are important in respiration, 
and probably in food- wafting. As to the alimentary system, it s 
typical, except that a caecum from the ventral anterior region of the 
hind-gut seems to represent the very early rudiment of a respiratory tree. 
In the youngest larvae the hydro-enteroccele (to the left) was already 
divided into two — the enterocoele, which divides into right and left sacs, 
and the hydrocoele, or water-vascular system. The coelom-sacs subse- 
* Bibliotheca Zoologica (Leuckart and Chun), Heft 19, pp. 55-75 (2 pis. and 
2 figs ). 
