INFUSORIA PARASITIC IN CEPHALOPODA. 193 
never found any which contained a single nucleus, as figured 
by Gonder. I thought at one time that I had done so, but 
later I was able to prove that the large uninucleate cells 
(fig. 16) which I mistook for Infusoria in the preparation 
were really giant amceboid cells from the cuttlefish’s kidney. 
Some of these cells attain a length of nearly 50 p. 
Neither in Chromidina nor Opalinopsis has any sign 
of conjugation been observed.! No sexual process of any 
sort 1s known. 
Equally unknown is the method of dissemination in nature. 
No cysts or resting stages have ever been seen. It is a 
curious fact that—like their frequent companions, the dicye- 
mids—the Infusoria are unable to live for more than a few 
minutes in sea water. How they reach their host is still a 
mystery. 
I should like to correct here the statement made by Gonder 
(7, p. 246) that the colour of the liver is an index of 
infection. As a matter of fact, the liver in a perfectly fresh 
uninfected cuttlefish varies in colour from dark red-brown 
up to creamy white, apparently according to the relative 
amount of cellular and non-cellular substance which it con- 
taius. In livers of very pale colour, only a few shreds of 
living tissue are to be found. Colour seems dependent 
mainly upon metabolism, not parasites, though these might, 
of course, affect it occasionally to some extent. 
The significance of the nuclear apparatus. 
A comparative study of the nuclear apparatus of Chromi- 
dina and Opalinopsis brings some interesting points to 
light. I will here indicate a few of these. 
As I have already shown, in both Chromidina and 
Opalinopsis the nuclear apparatus consists of a delicate 
network, composed of chromatin granules imbedded in a 
? 
' The figure given by Fettinger (6).showing “ conjugation” in Opali- 
nopsis is, as Gonder justly remarks, nothing more than a stage in division. 
