ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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corpuscles, characterized by the possession of numerous extremely large, 
highly refractive spherules, may be seen. In addition there may be 
seen a number of large, distinct, rounded nuclei floating freely in the 
plasma. These belong to blood-cells which are markedly distinct from 
the spherule-bearing corpuscles, and characterized by such extreme 
sensitiveness to certain stimuli that contact with a foreign body, such 
as glass, causes an explosive disruption of their protoplasm. These 
cells, which the author proposes to call “ explosive corpuscles,” can be 
fixed by osmic vapour or iodine. The spherule- bearing cells are 
identical with Ehrlich’s eosinopliile granules, and are to be called by his 
name. The average number of corpuscles in a cubic millimetre of blood 
is 286, but the variation is between 250 and 400. The normal ratio of 
granular to explosive cells is one to three. 
The explosive cells may be seen to undergo remarkable changes ; 
extremely fine pseudopodia are shot out, along which blebs of cell- 
substance rapidly travel, expand into a bubble, and burst. Sometimes 
only short blunt processes are formed, and sometimes the surface of the 
cell forms vesicles without processes. In any case there is an explosivo 
solution of the cell-substance. Meantime, the nucleus also suffers 
remarkable changes ; at first indistinct, it rapidly acquires distinctness, 
and changes which appear to bo of a clotting nature goon. The average 
dimensions of an explosive corpuscle appear to be 25-30 p. in the long, 
and 10-11 /j. in the short axis. 
The eosinopliile corpuscles, on the other hand, persist unchanged and 
may even retain their powers of movement for a long time, in a drop of 
blood, placed under a coverslip. They exhibit a marked distinction into 
ectosarc and endosarc ; they vary greatly in shape, and tlio number of 
the granules in the endosarc also varies considerably. The granules 
are extraordinarily refractive and very large, but they are not, as Ilaeckel 
thought, fatty. The author sets out at length the histological characters 
of the eosinophile cells, partly because it is necessary to do so to show 
that the explosive, eosinophile and basophile (to be mentioned im- 
mediately) cells differ not merely in the kind of granules they produce, 
but in the very nature of their cell-substances. 
The basophile cells, to use Ehrlich’s name, are those whose spherules 
have a profound affinity for basic pigments such as methylene or methyl- 
blue. They are very rare in the normal Crayfish, but are always found 
if the animal has been poisoned by certain substances ; in Daphnia, on 
the other hand, they are commonly present in the blood-stream. In the 
Crayfish they are, normally, important constituents of the special and 
peculiar tissue which forms a thick external sheath to some of the 
arteries ; they are large (as much as 65 /x by 37 /x) and irregular. 
The most striking fact with regard to the blood-corpuscles of 
Daphnia is that they are extremely generalized and primitive in their 
characters ; there is no sharp distinction into two kinds of blood-cells, 
and they perform functions which, in the higher animal, are relegated to 
cells which are no longer wandering. It is of importance that wg can 
regard the blood-cells of the more specialized type as a specialized tissue, 
or tissue sharply defined morphologically, and, probably, also possessed 
of equally sharply defined physiological characteristics. Each blood-cell 
of Daphnia includes within itself the characteristics of the explosive 
