CONJUGATION IN THE CRAYFISH, 
CAMBARUS AFFINIS 
E. A. ANDREWS 
Professor of Zoology, Johns Hopkins University 
EIGHT FIGURES 
The devotion of the individual to the welfare of the race is 
especially patent in such complex animals as the Arthropods, 
in which many organs and actions relate directly to the processes 
of reproduction. 
In many Crustacea the most complex of all the interactions of 
the individual with the environment are the interactions with 
individuals of the opposite sex. A study of the conjugation phe- 
nomena of such Crustacea should enable us to estimate the highest 
capabilities of these animals and to place them more accurately in 
the scale of being, than by study of organs and activities concerned 
merely with self-preservation. A comparative study of conjuga- 
tion might aid in the understanding of the relationships of groups 
of Crustacea. 
Since the meeting of the sperm and egg will not take place, 
under usual conditions, without the preceding phases of conjuga- 
tion, these become as necessar>^ for the race as the fertilization of 
the egg. 
The present paper is a description of the processes of conju- 
gation in a common crayfish, Cambarus affinis, in which the sexes 
differ in many organs and actions. 
The female not only lacks the male organs and instincts but 
possesses ovary and oviducts, a peculiar sperm receptacle in the 
shell, special glands used in connection with the care of the eggs, 
characteristic proportions of various parts of the body and char- 
acter of first abdominal limbs. The female also possesses special 
THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 9, NO. 2. 
