EFFECT OF SACCULINA UPON FAT METABOLISM OF HOST. 269 
and indebtedness to him for his continued advice and 
criticism both as to practical methods and theoretical 
interpretation. The work was done during my tenure of the 
Oxford University Biological Scholarship at the Zoological 
Station at Naples, from November to May, 1910-1911. 
My thanks are due to the staff of that institution (and in 
particular to Dr. Paul Mayer and Dr. Cerruti), for the ready 
way in which material was procured and my work facilitated. 
Lastly, I must thank the Trustees of the British Museum 
for leave of absence from my official duties. 
II. The Effect of Sacculina upon the Lipochrome and 
Fat Supply of Inachus. 
The blood of Inachus will be found according to my 
experience to be colourless or to exhibit one of two tints — a 
pink and a yellow. The latter are represented each in various 
degrees of intensity, and often seem to pass insensibly into 
each other ; the ultimate terms, however, of such a series 
are strongly characterised and clearly distinguishable. 
It will be convenient for the present to regard these two pig- 
ments as a single body — a lipochrome; for, whatever differences 
may exist between them they both exhibit a characteristic pro- 
perty of lipochromes, namely, solubility in fat or fatty 
substances, and for our immediate purposes this is their most 
important feature. By reason, then, of this solubility in fat 
we may regard lipochrome as a clue to the presence of fat in 
a given medium. The medium, in this present case, is the 
blood of Inachus, and, according as lipochrome is present, I 
consider fat to be similarly present. I must leave the 
converse of this open for the present — namely, wh ether fat 
is absent when lipochrome is likewise absent. 
This pigment is not a constant characteristic of the blood of 
Inachus. The following table gives in percentages the 
number of normal and sacculinised animals of both sexes 
