SPIROCHHTA BALBIANII AND SPIROCHATA ANODONTH. 41 
at the time with the appliances then available for such 
research. 
The nucleus in S. anodonte is much the same as 
that of 8. balbianii, though the organism is considerably 
smaller, and -the details are consequently much more difficult 
to discern. The organism also moves much more quickly, 
and there may be the added torsion of the body, in fixed and 
stained preparations, in the case of this smaller parasite. 
Nevertheless, we find the nucleus disposed over the general 
length of the body, and not marked irregularities present in 
the distribution of the chromatin, as figured by Keysselitz 
(4, fig. 15c). Such irregularities might be due to abnormal 
specimens or imperfect staining. Stress has already been 
laid on the unusual difficulty of differentiation in staining 
with iron-hematoxylin in such minute forms, which are too 
small for one to observe the details of differentiation under a 
Zeiss DD lens. 
There appears to me to be no evidence to support the 
queried suggestion of Keysselitz himself (4, fig. 13d) as to 
the marked contractility of the chromatin thread. I have 
never seen a condensed condition of the nucleus in any 
of the specimens of either of the Spirochetes which I have 
examined, although I have carefully searched for the same. 
I have not seen, then, in 8. balbianii or S. anodonte a 
concentrated central condition of the nucleus as figured by 
Schaudinn for Spirocheta (Trypanosoma) ziemanni 
(20), and which is so common in most Protozoa and the 
Metazoa. 
The achromatic spiral filament, which sometimes contains 
chromidia disposed along it, is probably homologous with the 
‘“‘karyosome ” of higher forms, for it consists of achromatic 
nuclear substance in which granules of chromatin may occur, 
as judged by the best chromatin stains, such as iron-hema- 
toxylin and gentian-violet. I have hesitated to make direct 
use of the word ‘karyosome” in my descriptions of the 
nucleus, pending the discovery of some further connection 
between the “diffuse” and the “‘ concentrated”? conditions 
