﻿MERRIMAN- NUCLEAR DIVISION 



with 4 spirals, others with 5; fertile cells not swollen, zygospore 

 oval. It also resembles S. majuscula Wolle. This material grew 

 in pure culture in a swamp in a low-lying pasture. 



Preparations of the 3 varieties show essentially the same 

 structures. C was noteworthy for great variation in number and 

 size of nucleoli. The 3 varieties show striking uniformity in forma- 

 tion and appearance of chromatic disks in approximately the same 

 numbers. It was found advisable to make sketches of nuclei 

 not at equal intervals of time, but at those periods when changes 

 in the form and density of the component parts were more mani- 

 fest. As some of these changes took place with great rapidity, 

 others only appearing as a slow evolution, many rough sketches 

 were made, not only following one nucleus throughout its changes, 

 but also in different nuclei, studying particular phases repeatedly 

 where changes were most rapid, to confirm interpretations made 

 upon one. This seemed necessary, as many of the appearances 

 were at variance with published results of other investigators. 

 The rapidity of the changes in the living material explains why we 

 get such variation in the fixed material. 



From the appearance of the first change in the nucleus until the 

 close of the reconstruction of the daughter nuclei, about an hour 

 elapses; in some cases, 80 minutes. As the phases merge into one 

 another, it is difficult to give precise time, but the following schedule 

 may be taken as a typical example: prophase 15 min., metaphase 

 5 min., early anaphase 15 min., late anaphase and telophase 30- 

 45 min. The changes in the nuclei are most marked and rapid in 

 the first 3 phases. In late anaphase and telophase, although 

 changes in translucency and shape occur, they do not result in such 

 great differences in position; hence frequent sketches with con- 

 stant comparison of observations were necessary to be assured of 

 these changes. Since the structural organization of the nucleus 

 is but the result of fixation of colloidal materials seen in living cells, 

 effort was made to find in the living cells the homologue of the 

 stained structure. 



The quiescent nucleus contains a central spherical body (fig. 1), 

 or more often in variety C two or more such bodies. This body 

 may appear bluish or slightly opalescent as compared with the 



