Cytology and Movements of the Cyanophycee. 273 
figure in the case of the Cyanophycez, harmonized with the 
mitotic process of division of the ordinary plant and animal 
cell nucleus, so that he could not have any doubt of the 
nuclear nature of the forms hitherto known as the central 
bodies, in spite of the lack of a nuclear membrane and 
nucleoli. (22) In the division of the cyanophycean cell the 
nucleus was always divided into equal halves, and there- 
fore could not be due to direct division or fragmentation, 
for in none of the places where fragmentation occurred in 
the higher plants did this occur. Again in fragmentation 
the division wall did not appear, while in the Cyanophycez 
it invariably followed the division of the nucleus. It there- 
fore was settled that a nucleus was present in the Cyano- 
phycez, and that it divided according to the usual mitotic 
methods. 
It is to be regretted that Hegler did not leave drawings 
to supplement the very excellent photo-micrographs which 
illustrate the paper. Photo-micrographs, especially when 
unretouched, are always true to nature, but there must be 
a great advance in the art of making them before they can 
be made to show the details of cytology that good camera 
lucida drawings reveal. They form a good adjunct to the 
illustration of such a paper, but should not be relied upon 
entirely. 
(2) GENERAL MorpHoLocy oF TyPEs STUDIED. 
As has been shown by the foregoing review of the litera- 
ture, the cell of the Protophycez is usually described as a 
protoplast composed of a central body and a peripheral part 
surrounded by a wall. This is as far as agreement goes. 
The composition of the central body, and whether it should 
be regarded as a nucleus, are points round which conten- 
tions have raged strongest. Most observers agree that the 
protoplast is granular, though some maintain that it is 
homogeneous. These granules are variously spoken of as 
