242 Phillips on a Comparative Study of the 



he formerly considered to represent the nucleus, he now 

 interpreted as very large microsomes which reacted like the 

 nuclei of the higher plants. The peripheral protoplasm he 

 found crowded with larger or smaller granules which 

 stained deeply with haematoxylin like chromatin granules 

 in other plants. This peripheral layer is what Schmitz 

 busied himself with mostly in his second and third (69) 

 papers, in the last of which he concluded that he was unable 

 to find any specially formed nucleus or chromatophore in 

 either the Cyanophycese or the Bacteria. 



It is interesting to note that in his earlier work, Schmitz 

 saw a homogeneous central portion which he called a 

 nucleus. There was also a granular periphery to the cell 

 which resembled a chromatophore. In his later works he 

 still found a central body, but because it broke up into 

 "microsomes," he no longer interpreted it as a nucleus, but as 

 granules which were composed of nuclear constituents. His 

 later works were given over to the study of the chroma- 

 tophores more particularly. These he also failed to find, 

 but attributed the function usually performed by such organs 

 in the higher plant cells to the general protoplasm of the 

 Cyanophyceae. 



Wille (85) worked principally upon Tolypothrix lanata, 

 which he stained with haematoxylin, preferably concen- 

 trated. He could make out a dark blue nucleolus, which 

 in nature is relatively quite large and colorless, and a pale 

 blue nucleus in an unstained cytoplasm. The nucleus 

 could also be seen in the granular cells when treated with 

 dilute acetic acid. He also succeeded in demonstrating an 

 intercellular continuity of the protoplasm in Stigonema com- 

 pactum, Ag. At the time of cell division, which he was 

 able to observe clearly, he found that each cell nucleus 

 divided into two nuclei, each having one or two nucleoli. 

 Thereafter the dividing cell wall was laid down. He did 

 not claim a nucleus for all of the Cyanophyceae, but regarded 

 it as always present in the higher forms. 



