Cytology and Movements of the Cyanophycece. 257 



elusions concerning Spirogyra were based upon very faulty 

 and insufficient observations of that organism. 



Zukal (100), working on Tolypothrix lanata, concluded 

 that the structures which Wille (85) termed "nucleoli" 

 were in reality a number of small cell nuclei, each sur- 

 rounded by a portion of cytoplasm, having arisen endo- 

 genously by division of the cell nucleus, but having no wall. 

 There might be as many as sixty-four of these present, all 

 connected by a network with the central body. These he 

 termed the nuclei, founding his conclusions on their power 

 to divide. He cited, however, his difficulty in getting con- 

 stant results, but this, as has been pointed out above, should 

 scarcely be considered seriously, except that care must be 

 taken, by the use of several reagents, as there suggested, to 

 avoid the formation of artifacts. In a later work (99) 

 Zukal again called attention to these granules, which he 

 now identified with the "red granules" of Biitschli. They 

 stained very lightly with safranin, eosin or hsematoxylin, but 

 hot methyl blue brought them out very strongly. They did 

 not really disappear when treated with 5 per cent, potassium 

 hydrate, chloral hydrate or i per cent, hydrochloric acid, but 

 swelled more or less and seemed to disappear. He concluded 

 that the granules were coagulated albumen, which formed 

 the cell nuclei and surrounded the central clear mass of cyto- 

 plasm. He did not enter minutely into the question of cell 

 division or of the nucleus, but his conclusions on this point 

 were as follows: "In each cell nucleus two nucleoli are 

 formed after each simple (amitotic) division. This occurs 

 mostly at night. The division of the nuclei ('red granules' 

 of Biitschli) may proceed without the division of the cell." 

 In regard to the chromatophore, his definition was, "a defi- 

 nite, demarcated part of the protoplasm, saturated with the 

 characteristic coloring matter of the plant." He considered 

 such a chromatophore, formed of an exceedingly delicate 

 reticulum of fine granules, to be present surrounding the 

 colorless cytoplasm of the Cyanophycea:. Still later Zukal 



