Tue Microscope. 159 
As in the case of the red corpuscles, the question of a cell-mem- 
brane may be raised in regard to the plaques. 
Still another point of resemblance between the red corpus- 
cles and plaques is that, under certain circumstances the latter 
will shrivel and become crenate; and Kemp says that it is quite 
a usual thing to see both plaques and red corpuscles caught at 
one end and drawn out by a current so as to present a long, 
pear shaped or even threadlike appearance. According to 
Hayem, again, the plaques contain haemoglobin; a view which 
is supported by Mayet and Laptschinsky, the latter having des- 
cribed corpuscles about one-third the size of the red corpuscles, 
which are sometimes more strongly colored than usual, and 
sometimes colorless. Riess, Bizzozero, Laker, Hlava, Halla and 
Schimmelbusch take the view that the plaques are without 
color, and Kemp has tried in vain to find hzemoglobin in them, 
even with the double staining fluid of carmine and indigo-car- 
mine, which is claimed to stain green any cell containing 
hemoglobin. Another point of relation between the plaques 
and red corpuscles, pointed out by Hayem, Bizzozero and Lav- 
dovsky, is that in different animals the size of the plaques al- 
ways varies in the same ratio as that of the red corpuscles. To 
this point Kemp adds that in trying to get a preparation from 
which to make a photograph of the plaques, he tried ten differ- 
ent staining fluids on the blood after hardening in osmic acid, 
and an every case the plaques and red dises stained proportion- 
ately. 
Hayem further supports his hematoblast theory by the as- 
sertion that in pathological conditions of the system where 
‘“new blood” is demanded, we may always find the plaques in 
increased numbers—which fact had already been stated by 
Reiss. But there is an objection to this assertion which is so 
great as almost to necessitate a Scotch verdict. Kemp says: 
“ The sources of error in all numerical determinations of the 
plaques are very great, on account of the tendency which these 
elements have to adhere to each other or to any foreign body 
with which they come in contact. I was early led to see that 
for this reason numerical determinations, where the blood had 
to be measured, were practically of little value. The same 
point has been made by Schimmelbusch, who, in addition to 
