SPIROCHHTA BALBIANII AND SPIROCHATA ANODONTE. 9 
It may be mentioned that the reproductive organs of the 
oyster (25), and of infected Anodons were examined by me, 
but no Spirochetes were found therein, although Koch (16) 
found S. obermeieri in the ovary and ova of the tick. It 
is quite possible that the oysters examined by me were not 
mature. 
Specimens of Atax bonzi, Clap. (26), occurring in the 
mantle-cavity of Anodonta cygnea, probably as com- 
mensals (27), were found to contain no Spirochetes, though 
S. duttoni occurs in ticks (14a). But S.anodonte is a 
parasite of the gut, and probably primitive in its habitat. 
Merruops. 
(a) For Fresh Material. 
I have made a special point of examining these two Spiro- 
cheetes in their natural environment as far as possible. This 
method does not appear to have been followed in the case of 
S. balbianii to any great extent by previous observers, 
Perrin excepted, judging by their published statements, while 
there is no account of an examination of 8. anodonte in the 
living state. 
When a style was present the freshly extracted structure 
was mounted in a drop of sea water or fresh water in the case 
of Ostrea and Anodonta respectively, and placed in a 
moist chamber. The organisms were often thus kept alive 
from three to six hours, while the style was examined in 
sections in the laboratory at a temperature above that of the 
sea or the fresh water in which the hosts lived. 
‘In the case of portions of the style the inner fluid contents 
were pressed out as far as possible with a fine scalpel held 
flat, or with a triangular-headed lancet as recommended by 
Perrin. The outer and firmer part of the style, to which the 
parasites often cling for a time, may, after a while, be separ- 
ated out of the preparation if possible. But on the whole it 
is best to fix the smear wet with osmic vapour as quickly 
as possible. 
