304 H. E. JORDAN 
phase and metaphase groups of chromosomes of multipolar 
spindles. They have assumed a correspondence with the typ- 
ical multipolar mitoses of neoplastic tissues. But no one, with 
the exception of Denys, has actually claimed a consummated 
mitotic division. The other investigators have only ventured 
to interpret these mitotic simulacra as a method by which the 
polymorphonucleated nucleus of the giant-cell becomes still 
more complex. No one has claimed the presence of spindles 
in connection with these figures. Nor has any one apparently 
seen the significance of the reduced amount of cytoplasm of 
the cells containing these alleged mitotic figures; nor taken 
account of the obviously degenerating naked nuclei in their 
seriations of stages in the life-history of these cells. The absence 
of spindles alone, however, marks these figures at once as some- 
thing different from the multipolar mitoses of neoplasms, and of 
morbid and experimentally modified tissues. 
Since Wright (18) published his more complete paper, with 
convincing colored illustrations (710), on the origin of blood- 
platelets from the cytoplasm of the medullary giant-cells, we 
have been furnished a new basis for the interpretation of these 
various nuclear modifications. Wright’s conclusion regarding 
the genesis of blood-platelets has now had confirmation at the 
hands of at least three subsequent independent investigators; 
Bunting, (8) Downey, (6) and Jordan (11, 14). Blood-platelets 
arise by a process of pseudopod constrictions, and by cyto- 
plasmic fragmentation, from hemogenic giant-cells. The former 
method of origin is generally restricted to the cells with the 
more vesicular nuclei (figs. 1 to 4); the latter method to those 
cells having deeper staining, more complex and less regular 
nuclei (figs. 8 to 11 and 20 to 21). It was shown in previous 
studies that blood-platelets arise by a similar method from sim- 
ilar cells, and even from the parent hemoblasts, in the yolk-sac 
of the 10-mm. pig embryo (14); and that leucocytes generally, 
both lymphocytes and granulocytes, in the red bone-marrow of 
the frog possess the capacity of constricting off platelet-like 
bodies (13). The conclusion was there stated that platelet 
formation is a by-product of the normal activity of leucocytes 
and of the disintegration of degenerating leucocytes. 
