Royal Microscopical Society. 67 



amoeba-like masses of protoplasm without nuclei. Although their 

 amoeboid movement had ceased, the molecular one of the pale 

 granules of the protoplasm wa? still very active, and continued, 

 after the addition of water, for a considerable time.- Dark-bordered 

 granules were not present. The office of the layer of protoplasm of 

 the colourless blood corpuscles would then be to nourish the nucleus 

 contained within it, as well as to promote the metamorphosis of the 

 latter into a coloured blood corpuscle. It is more difficult to assign 

 a function to those groups of dark-bordered, dancing and oscillating 

 granules, which are observed upon the surface of the protoplasm of 

 many of the colourless blood corpuscles. If, however, we consider 

 that similar granules are met with in other tissues, especially in 

 such in wliich the molecular changes are particularly active, we 

 might almost assign to them a function relating to these changes. 

 This is the case in the ganglionic bodies of the nervous system, 

 where they are met with in the form of accumulation of pigment 

 granules upon the body itself, and sometimes also upon the pro- 

 cesses. In the upper layer of the cortical substance of the cerebrum 

 they are also observed, accumulated in the vicinity of certain groups 

 of free nuclei, which they frequently entirely obscure. In all these 

 places they appear in the same oblong form, and when accumulated 

 in a mass form a yellowish spot. In the blood corpuscles, however, 

 they are colourless. 



In reviewing the process of generation and formation of the 

 blood corpuscles of man, described in the preceding pages, in later 

 life as well as in early embryonic life, it is obvious that the organs 

 in which it takes place truly represent nothing else but glands. 

 The structure of the follicles of the umbilical vesicle, in which the 

 first embryonic blood corpuscles originate, corresponds in every 

 respect to the simplest type of a gland. The structure of the 

 spleen, on the other hand, seems, at a superficial glance, not to 

 correspond at once to such a type. But if we imagine the fibrous 

 layer which supports the gland cells to be converted into a reticu- 

 lated fibrous structure with wide meshes — as is found in the spleen 

 — and look upon the free nuclei and cells laying in the interspaces 

 of this structure as gland cells, the comparison, even here, will not 

 be difficult. We can therefore look upon the blood corpuscle as a 

 gland cell. Even so, as the gland cells transform in their interior 

 certain materials, derived from the liquor sanguinis, into other sub- 

 stances destined to subserve various purposes in the organism, just 

 so is it the office of the blood corpuscles to promote within them- 

 selves the metamorj^hosis of certain elements. The difierence 

 between the two would only consist therein, that, while the gland 

 cell in general discharges its secretion upon the surface of a mem- 

 brane, the matured hlood corjniscle gives hack directly to the liquor 

 sangmmSjhy its final dissolution, its secretion, consisting of its oivn 



