IRON COMPOUNDS IN ANIMAL AND VEGETABLE CELLS. 207 
of the blue and red reactions, and thus appearing in sharp con- 
trast with the enclosed nucleolar body coloured light blue. 
It is chiefly in the nuclei of the glandular cells that one finds 
these nucleolar bodies, and they are most distinctly seen in 
large nuclei, as, for example, those of hepatic and renal cells 
and of the intestinal epithelium of Necturus lateralis. 
They are very rarely seen in the nuclei of the muscle fibre 
and in those of the cutaneous epithelium of the same animal, 
while they are never present in those of leucocytes or lymph 
cells, or in those of the red blood-corpuscles. In the search 
for them in all these elements the greatest assistance is 
obtained from the employment of eosin, which, in sections 
exhibiting the Prussian blue reaction, gives these bodies an 
ochre-red colour, while the parts showing a dark-blue reaction 
are unstained by it (fig. 47). In the nucleus of the glandular 
cell which is passing into the mitotic phase, the nucleolar body 
disappears, apparently by solution into the chromatin threads, 
for in the nucleus of a renal cell, in which the meridional 
disposition of the chromatin filaments obtained preparatory to 
the formation of the loops, I saw, attached to one of the fila- 
ments and partly embraced by its substance, what appeared to 
be the remains of sucha body. In later stages of mitosis 
not the slightest evidence of this body or of its remains can 
be observed. 
Whether the iron which these bodies contain is that of a 
small quantity of chromatin dissolved in them, I am unable to 
say. The fact that they take sometimes a very feeble stain 
with hematoxylin, seems to indicate that they may contain a 
small amount of chromatin. The iron in them is held neither 
more nor less firmly than in the typical chromatin elements, 
since in hepatic nuclei containing them, prolonged treatment 
with ammonium hydrogen sulphide in the warm oven does not 
result in demonstrating any difference, except in the amount 
of iron in the one and in the other. The substance which 
holds the iron does not possess the slightest affinity for 
safranin, but attracts eosin as no other cellular con- 
stituent does, and in these properties, as well as in the 
VOL. 38, PART 2,——NEW SERIES. O 
