252 University of California Publications. [Botany 



a number of minute, globular or somewhat irregularly shaped 

 chromatin granules." He states that both these substances stain 

 with the "standard nuclear stains, e.g., iron haematoxylin and 

 Flemming's triple stain." During mitosis all the characteristic 

 structures are present, including: spindle fibers. The chromo- 

 somes, which are constant in number for each species, divide 

 crosswise in mitosis. 



To explain his interpretation of the spindle and its origin, I 

 quote his sixth conclusion, p. 36: "The kinoplasmic achromatic 

 portion of the central body constitutes a spindle, which has the 

 shape of a flattened disc in the narrow celled species ; and in the 

 longer celled forms, of a broad-poled, somewhat cylindrical fig- 

 ure; or in still others, narrow-poled and spindle-formed. The 

 achromatin consists of a central spindle, which is often very 

 densely fibrous, between the dividing chromosomes, and a portion 

 leading from the chromosomes to the cross-walls, which corre- 

 sponds to the mantle fibers in position and apparently in func- 

 tion." 



Conclusion seven reads as follows : "A spireme arrangement 

 of the chromatin granules is also evident in the preliminary nu- 

 clear changes. The segmented spireme in Gloeocapsa appears to 

 consist of a simple, more or less spiral thread, having about eight 

 chromatin granules held by the linin, and situated in the middle 

 of the cell, with its long axis corresponding to the long axis of the 

 cell." 



' ' In the filamentous species the spireme apparently consists of 

 a much convoluted thread, and it is further probable that it also 

 is made up of a definite number of distinct chromatin granules, 

 arranged along a linin thread." 



From conclusion nine I quote the following concerning the 

 number of chromosomes : — 



1 ' The number of chromosomes in the cells of the same species 

 is constant. . . . Each chromosome apparently corresponds 

 to a simple chromatin granule of the spireme thread. Should 

 this prove to be true, then this presents the hitherto unrecorded 

 phenomenon of a chromosome which consists of a single chromo- 

 mere. ' ' 



