422 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VoL. VI. 
germinating cells and neuroblasts with diffused chromatin, shows all 
stages in the process of transformation and diffusion of the chromatin. 
This circumstance enables one to be sure that the gradual loss of 
affinity of the nucleus for basic dyes is not due to overstaining in 
eosin, for after the chromatin begins to change, an overstaining with 
eosin will make it red, but a shorter time in the eosin will colour it pur- 
plish. If one examines a section in which all stages of the diffusion of 
the chromatin are seen, one can easily see the great affinity the nuclei of 
the nerve cells next the medullary canal have for toluidin blue. The 
nuclei of cells lying farther from the canal have less and less affinity for 
basic dyes, but one can observe that with this loss of affinity on the part 
of the nucleus for these dyes, a substance with marked affinity for them 
appears in the cytoplasm. This substance is first seen as a thickened 
nuclear membrane, but as more of it diffuses from the nucleus it takes 
the form of a distinct cone in the cytoplasm forming a cap on the 
nucleus. 
These observations have been confirmed on the cells of the cortex, 
cerebellum and spinal ganglia of mammals and also on the cells of the 
chicken. The chick embryos are not as suitableas mammalian embryos 
for following this process, on account of the general distribution of yolk 
nucleo-proteids, but the stages can be distinctly observed. 
The chromatic material appears in the cytoplasm of the cells of the 
medulla before it appears in those lower down in the cord, but my 
observations on the rate of the development of the material in the 
different centres are incomplete. 
The action of dilute alkalies on the cell varies with the degree of its 
development. At a stage such as is represented in Figure 21 the action 
of alkalies is similar to their action on adult cells. After treatment with 
alkalies the cell body would not stain with toluidin blue or did not con- 
tain iron, but the body of the cell still remained. If the view of Held 
and Biihler regarding the nature of the Nissl granules is correct, then the 
whole cytoplasm should have disappeared. 
Alkalies are very slow in altering the staining powers of the chromatin 
in mitosis. The nuclei of germinating cells and of the nerve cells in 
which the kinetic chromatin was only slightly altered, contained a large 
quantity of material that stained with toluidin blue and proved to be 
iron-holding, after small pieces of tissue, that had been fixed in alcohol, 
had been treated with potash (0.2//) for six days. In this same solution 
the Nissl] granules had been altered so that they would not give their 
