4 PROF. E, A. MINCHIN ON PROTOZOAN [Jan. 12, 
lengthy and detailed study of the life-history of Trypanoplasma 
cyprini (“ borreli”). It is, perhaps, for this reason that Keysselitz 
was unable to distinguish more than one species of Trypanoplasma. 
The deformation subsequent on drying is entirely avoided if 
the smear be placed as quickly as possible, immediately after 
smearing and before any appreciable amount of drying has taken 
place, into a stoppered tube or bottle containing a few drops of 
osmic acid, 4°/, solution. It should be exposed to the vapour for 
30-60 seconds, and then transferred, with or without drying, to 
absolute alcohol. After the fixation with osmic vapour the drying 
does not deform even the trypanoplasms, and the natural form, 
size, and appearance of these flagellates are, in my opinion, better 
preserved by this method than by any other. The osmic-fixed 
smears stain well with Giemsa’s stain, but are apt to stain rather 
too darkly and, in the case of large fleshy forms of the parasites, 
to become very opaque. Speaking generally, they should be 
stained for a much shorter time than the preparations dried off 
before fixation. 
The weak point of the preparations stained by the Romanowsky 
method, whether dried before or after fixation, or not dried at any 
time, lies in its effects on the nuclear apparatus. I hope to discuss 
this point in greater detail in a memoir which I am preparing on 
the structure of Trypanosoma lewisi. I will say here only that 
the Romanowsky stain, m its various modifications, gives results 
with regard to nuclear structure which are not capable of uniform 
interpretation, and which, in my opinion, are untrue and mis- 
leading. I believe the defects of the stain to be due principally 
to the fact that the red dye or dyes in the stain are precipitated 
not only in, but around, certain objects in the preparations ; with 
the result that the kinetonucleus, for example, appears many times 
its real size, while in the trophonucleus minute, almost ultra- 
microscopic granules become enlarged to coarse granules obscuring 
the true structure. This effect is not due to the drying, since it 
is to be observed in preparations stained by the Romanowsky 
method and mounted in Canada balsam without being dried at 
any stage of the process. I believe, however, that the process of 
drying, whether before or after fixation, may and does add greatly 
to the falsity of the nuclear results obtained by the stain. While 
osmic vapour fixes very perfectly the cytoplasmic portions of the 
body, it apparently leaves the nuclear constituents unfixed and in 
a fluid condition. Hence, while the general structure of the body 
is very perfectly preserved, even when dried, after osmic fixation, 
the nucleus remains in a fluid state and hable to deformation. 
That, at least, is the impression which a comparison of different 
methods gives me. 
For interpretation of the results obtained ‘by the Romanowsky 
stain, it is very instructive to compare the totally different results 
obtained by staining the same objects with Heidenhain’s iron- 
hematoxylin. For this it is necessary, however, that the smears 
snould be suitably fixed and that they should have never been 
