It must hence be concluded that an analogous process may go on during life, that these halos are the expression of a vital secretion of the substance of the mast cells externally[24].
A condition that Prus has brought forward in the so-called purpura of the horse, is also to be interpreted as a secretory process of the mast cells. He describes young mast cells from the hæmorrhagic foci of the wall of the gut, on the margins of which bodies of various sizes appeared, and which differ essentially from the mast cells themselves by their staining. Nevertheless from their whole configuration and position it is evident that these bodies have arisen in the mast cells themselves; and Prus comes to the conclusion "=that the degenerating young mast cells secrete a fluid or semi-fluid substance, which as a rule sets on the surface of the cells, but also, more rarely, in their interior=."
Evidence that the substance of the granules is given off externally may sometimes be seen in the polynuclear neutrophil or their analogues. Thus in rabbit's blood in which he had experimentally produced leucocytosis, Hankin found a distinct progressive decrease of the pseudoeosinophil granules on allowing the samples of blood to remain some time in the thermostat. Further in suppurating foci in man, especially when suppuration has lasted long, or the pus has remained for some time in the place in question (Janowski) a rarefaction almost to complete disappearance of the polynuclear neutrophil granules occurs, and is to be explained by a giving up of the granulations to the exterior.
These facts and considerations, on the whole, lead then to the conclusion, =that in general the granules of the wandering cells are destined for excretion. This elimination of the granules is probably one of the most important functions of the polynuclear leucocytes.=
[20] _Farbenanalytische Untersuchungen_ XII. _zur Geschichte der Granula_, p. 134.
[22] Altmann's freezing process would be similar to the advance always insisted on by Ehrlich. It offers such great technical difficulties, however, that it has up to now been little used.
[23] The cause of these misunderstandings is the tinctorially different stages of development of the granules, as we have fully explained above. How little adequate tinctorial differences by themselves are to settle the chemical identity of a granulation, is at once evident on consideration of the granules of other organs. No one surely would assert, that a liver, muscle, or brain cell could occasionally secrete trypsin, simply because the granules of the pancreas stain similarly and analogously to those of the cells mentioned. We would here expressly insist that we only assume a distinct character for each kind of granulation, in the strict sense of the term for the cells of the blood, since they possess a relatively simple function. In very complex glandular cells, however, with various simultaneous functions, several kinds of granules may be contained.