104 

 REVIEWS 



Gardner's Cytological Studies in Cyanophyceae * 



The many difficult questions as to the minute structure of the 

 blue-green algae have been thoroughly reviewed and carefully 

 studied by Dr. Gardner and his results are clearly set forth in a 

 paper which appeared last November in the University of Cali- 

 fornia Publications. His mvestigations have been concerned 

 chiefly with fifty-lhree species representing many genera and 

 most of the families of the Cyanophyceae. With this broad 

 view of the field, there is naturally a better opportunity of reach- 

 ing just conclusions than in the more common cytological 

 method of studying only a few forms. Dr. Gardner found that 

 with proper treatment everything of essential importance in the 

 cells of these small plants may be seen without making microtome 

 sections and finally came to use the microtome " only to supple- 

 ment and check results obtained without it." The principal 

 points as to which there has been disagreement among observers 

 involved the existence of nucleus and chromatophores, the struc- 

 ture of the cytoplasm, the structure of the nucleus, if it exists, 

 and its behavior during cell-division. Some of the more interest- 

 ing results of the present investigation are summarized by Dr. 

 Gardner as follows : 



" The cell of the Cyanophyceae contains a nucleus which in 

 some species is sharply delimited from the surrounding cyto- 

 plasm, while in others the differentiation is much less marked." 



" In all the species studied, with the possible exception of 

 SynccJiocystis, the nucleus divides amitotically, beginning at the 

 periphery an.d gradually proceeding to the center." 



" There is no definitely organized chromatophore, the cyto- 

 plasm holding the coloring matters." 



" No protoplasmic continuity between the vegetative cells has 

 been demonstrated." 



" A new type of nuclear division has been discovered in Dermo- 

 carpa, in which the nucleus breaks up simultaneously into a large 

 number of daughter nuclei by a process of amitosis," 



* Gardner, Nathaniel Lyon. Cytological Studies in Cyanophyceae. University 

 of California Publications. Botany 2 : 237-296. //. 21-26. lO N 1906. 



