Cytology and Movements of the Cyanophycecz. 273 



figure in the case of the Cyanophycese, 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 

 nucleoh. (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 Cyanophyceae 

 it invariably followed the division of the nucleus. It there- 

 fore was settled that a nucleus was present in the Cyano- 

 phycese, and that it divided according to the usual mitotic 



methods. 



It is to be regretted that Hegler did not leave drawuigs 

 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 Morphology of Types Studied. 



As has been shown by the foregoing review of the litera- 

 ture, the cell of the Protophycese 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 



