CONJUGATION IN THE CRAYFISH, CAMBARUS AFFINIS 243 
without these movements and probably has but a small respiratory 
exchange in comparison with the more active male during the 
conjugation. 
But while the female is so inert the nervous system may be re- 
ceiving stimuli of some sort. The two minute and apparently 
useless limbs of the first somite of the abdomen are seen to reach 
up in the water to the stylets of the male, and in one case to 
touch the endopodites that had sperm upon them. Possibl5^ some 
general sensations are received through these palp-like limbs. 
Possibly study of these organs would show that they are of use 
as sense organs, though of no great importance. Herrick has 
suggested that in the female lobster these limbs have been reduced 
to prevent eggs being attached to them, as that would interfere 
with the closure of the abdomen over the other eggs; but even 
granting this, the limbs may have a sensory value, both in con- 
jugation and in egg-laying, though they are not necessary, as I 
have proved by removing them. After conjugation these little 
organs reach to the sperm plug, but it seems improbable that the 
female is aware of the success of conjugation. 
During conjugation there are sometimes twite hings of the 
muscles of the abdomen and when the stylets happen to be thrust 
against the soft membrane posterior to the annulus there are 
twitchings of the body of the female that indicate that the 
apparent hypnotic state is not one of paralysis of all the body. 
Again since the annulus is pushed dorsally by the stylets, which 
enter it so firmly that when the male is pulled away the annu- 
lus is drawn out as far as the cuticle will allow, it may be that 
the female has some sense of the change of pressure in that 
region. 
Turning to the activities of the male, they may, as above 
stated, be resolved into many different phases, the first of which is 
the seizing of the female. Most of the males in the mating season 
seem ready to seize any other crayfish, and if they seize females the 
rest of the conjugation generally follows. The female is grasped by 
first one and then both of the chelae, though a mutilated male with 
only one chela can accompHsh conjugation. One chela often 
seizes the head of the female, but here is much variety in the modes 
