1909. | BLOOD-PARASITES OF FRESHWATER FISHES. 9) 
characterized morphological species, each quite distinct from the 
only specimen of 7. borreli of the rudd that I have seen. 
Considering the great variability im size of these parasites, it is 
remarkable that so many authors should base their specific descrip- 
tions so largely on measurements. A naturalist, for imstance, of 
the attainments and experience of my friend M. Brumpt (to whom 
I owe my first lesson in the art of staining trypanosomes in 
blood-films) can hardly have thought such measurements to be of 
any real validity as specific characters. 
In considering the minute structure of these parasites we may 
begin with the nuclear apparatus. As I have stated above, the 
use of iron-hematoxylin as a stain permits of a uniform interpre- 
tation of the appearances; and I think it is a very important 
point, that it is possible to give in general terms a description of 
the nuclear apparatus which will apply to trypanosomes and try- 
panoplasms alike. In both cases we find a kinetonucleus and a 
trophonucleus, the first named being relatively very large in the 
trypanoplasms, small in the trypanosomes. Near the kinetonucleus. 
are found the minute blepharoplasts or basal granules of the 
flagella, two in 7rypanoplasma, one in Trypanosoma*. 
The kinetonucleus in both cases appears as a dense body stained 
a uniform deep black after iron-hematoxylin. I have not been 
able to detect any structure init. When the stain is over-extracted 
it appears to come first out of the periphery of the nucleus and 
last of all out of the central part, but this appears to me to be 
merely the expression of the dense texture of the kinetonucleus, 
and not to indicate any structural difference between central and 
peripheral regions. After the Romanowsky stain the kineto- 
nucleus appears very much larger than it does after iron-hema- 
toxylin; it may be four or five times as large (compare figs. 33— 
36 and 57-64; 40-43 and 66-72; 1-7 and 78-85, &.). As I 
have stated above, I believe this result to be due to the fact that 
the stain forms a deposit round it. With iron-hematoxylin the 
size of the kinetonucleus is quite uniform if the stain be not over- 
extracted, i which case also the true size is indicated by a clear 
space surrounding the central portion stained black. 
The blepharoplasts appear usually as very minute dots, scarcely 
thicker than the flagellum, after iron-hematoxylin. There 
appears to be a band of fibril connecting the kinetonucleus and 
the blepharoplasts, which is shown by iron-hzematoxylin, at a 
certain degree of extraction (fig. 98); it stains much less deeply 
than the kinetonucleus. After the Romanowsky stain the blepharo- 
plasts often appear much larger and may be conspicuous ; hence 
this stain is useful for demonstrating their existence, although it 
* Tadhere, in my descriptions of the structure of these parasites, to the termino- 
logy of the organs suggested by me in the ‘Quarterly Journal of Microscopical 
Science,’ li. pp. 171-174, text-fig. A; with the difference that I employ the term 
“karyosome”’ for the intranuclear body there termed “centrosome.” To judge by 
its behaviour during nuclear division, the karyosome of a trypanosome probably 
contains a true centrosome or “ centriole.” 
