SEXUAL ACTIVITIES OF THE SQUID 345 
mantle chamber of this species, they cannot be considered as nor- 
mally functional. He seems led to this conclusion by finding 
sperm reservoirs attached to various portions of the bodies of the 
animals as well as in the immediate neighborhood of the mouths 
of the oviducts. It would seem more likely in the light of the ob- 
servations here recorded for Loligo, that a copulation that leads to 
the filling of these receptacles is normal and that the sperm so 
stored may be used in fertilizing the eggs. 
It is certainly hard to conceive by what steps a complicated 
method of transferring sperm that has led to the formation of a 
hectocotylized arm and complicated spermatophores might be 
perfected. The modification of different arms for copulation by 
different cephalopods further increases the difficulty in under- 
standing the history of hectocotylism as a whole. 
While evidence that bears directly upon the history of the hecto- 
cotylism seems to be lacking, such complications are so frequently 
considered to be impossible to explain by known evolutionary 
factors that it may be well at least to consider the great difficul- 
ties presented.by such structures. It must not be supposed that 
in so doing I put myself in the position of defending a thesis. This 
would be too much like the methods employed by many of the 
Greek philosophers who needed little or no basis of fact upon which 
to build. My only reason for considering the matter here is to 
show that, with all the difficulties, the condition of hectocotylism 
among modern cephalopods cannot be considered beyond the pos- 
sible range of evolutionary factors. 
Among the Dibranchiata the arms that show hectocotylism are 
the first, the third and the fourth on both sides of the body. Some- 
times more than a single one is affected. In such cases the modi- 
fied arms may be symmetrically placed on the two sides of the 
body, or they may be adjacent arms on the same side of the body. 
Steenstrup attempted to base the classification of cephalopods 
upon their hectocotylized arms but Brock and Hoyle have shown 
that forms whose general body structure would seem to indicate 
relationship, do not always have homologous arms modified. 
While the arm is usually constantly on one side for all members 
of a genus, unless both sides are modified as not infrequently hap- 
