308 DR THOMAS H, BRYCE ON 
propose to enter into a detailed discussion of all the theoretical points on which my 
observations bear. The problems relating to the histogenesis of the erythrocytes, and 
the origin and interrelations of the leucocytes, will be dealt with in the second part of 
the memoir. Here I shall only deal briefly with certain more strictly cytological con- 
siderations, and refer to certain conclusions which the contrasting characters of the 
erythrocytes and leucocytes seem to warrant. 
It is to be noted that as the close juxtaposition of the blood elements has exposed 
them to identical conditions both of fixation and staining, the different pictures pre- 
sented afford a secure ground for comparative study. 
In the matter of the protoplasm, the material affords examples of all grades between 
a purely structureless condition and a coarse reticular formation. I have already 
sufficiently discussed the reticular structure of the erythrocytes, and expressed my 
belief that it represents an actual disposition of the protoplasm in the living cell. 
During mitosis it has been demonstrated that this framework is converted into the 
achromatic figure. In the leucocytes which show a definite but extremely delicate 
reticulum, this plays the same part in mitosis as the large network of the erythrocytes. 
The appearances differ in degree only, not in kind, and therefore there is no sharp 
line to be drawn between the two, whether one accepts the reticular or the alveolar 
hypothesis. It would seem to be more or less a matter of the relative proportion of 
active and passive elements, and of variations in consistency. 
The differential staining of the chromatin of the erythrocytes is a point of suggestive 
interest, but I am not competent to deal with the questions of cell chemistry involved. 
While the behaviour to iron hematoxylin might be due merely to differing physical 
properties, the reaction to the other dyes indicates a chemical differentiation of the _ 
chromatin which must be in some way connected with the functions of the corpuscles. 
The most suggestive of the contrasts observed is that in the characters of the 
centrosomes. . 
In the erythrocytes, which are passive bodies, in the resting stages there is no | 
centrososome discernible. The body is related only to the mitotic phenomena, and | 
when the kinetic phase is past it disappears as such. Every fact in its history points 
to its bemg merely the central point of a cytoplasmic condensation, whatever may be 
the physical or chemical changes involved. 
In the leucocytes the centrosome always stains with the cytoplasm. In its full 
panoply of sphere and aster it is only seen in the leucocytes which undergo amceboid 
movements. This fact supports the view that it is related to these movements, and | 
this is actually demonstrated by leucocytes caught in amceboid movement (fig. 21, 
Pl. IL). That some cytoplasmic activity exists, centred on the centrosome, is clear, 
but what the nature of the activity may be is another matter. 
My observations are too few to warrant my going into this question, One would 
require to see many more amceboid leucocytes at all stages than I have done to form 
any opinion on the general question. I put forward the facts I have observed merely | 
