ane 
39 
groups, growing as well as regenerating tissues and found many 
nuclei in them which divided amitotically. According to FLemMina’s 
conception, which was especially supported by Ziener and vom Ratu, 
this was only possible in pathological cases; according to Crump it 
occurs in normal tissues as well, particularly when they are growing 
rapidly. 
ParrErsON observed the same with the tissues of the embryos 
of the domestic fowl. 
Without detracting from the accuracy of Cuitp’s and Patrrsrson’s 
observations I wish to point out here that still another viewpoint 
is possible which may perhaps in some cases offer an explanation 
of the small number of karyokineses in growing tissues. 
It is a well-known fact that if one wants to see the cells of 
spirogyra dividing, these tissues must be fixed during the night. 
Good observations of nuclear division in the rootlets of hyacinths 
and onion bulbs—a favourite botanical material—can be made if the 
rootlets have been fixed between ten and eleven in the forenoon. 
The question may now be put whether also in animal tissues a time 
may be fixed at which nuclear divisions are most frequent and 
next whether a period in the proeess of nuclear division can be 
noticed. 
Material. To serve as material for the investigation six newborn 
cats were chosen from two litters and killed on the second day of 
their life respectively at D/s Get and „10°/ vp’ 
and at A 7: and 10'/, a.m. 
The following tissues were examined : 
mesentery, (bits of which were spread on a slide), fixed with 
Carnoy stained with ironhaematoxylin-eosin ; 
cornea, fixed in mercury bichloride formalin, stained with iron- 
haem.-eosin and cut into sections of 5 u. 
small intestine, fixed with Carnoy stained with ironhaemat.-eosin 
and cut into sections of 5 u. 
liver, fixed with ZeNkKer’s liquid and stained with ironhaemat.- 
eosin, cut into sections of 5 u. ' 
Mesentery. Different pieces of the membrane were examined in 
succession and their nuclei counted by means of an “Okular- 
Netzmikrometer’’., 
The following table shows the number of nuclear divisions and 
the various stages of the process of division. 
