348 



THE AMERICAN NATURALIST 



[Vol. XL 



receding telson like an apron that covers over the eggs and prevents 

 them from falHng out even when the female turns right side up. 

 This is the condition indicated in Fig. 5 of the preceding article 

 in this journal. 



While the eggs are emerging, the crayfish is almost motionless, 

 lying supine with stiffly outstretched limbs and open claws as if 

 dead. If now removed from the water and held in the hand the 

 crayfish responds but little and the flowing out of eggs continues 

 and may be more closely watched. 



The mouths of the oviducts are widely open and remain fixed 

 in that state when the crayfish is plunged into boiling water. It 

 is then seen that the oval membrane that usually covers the open- 

 ing is pulled outward like a curtain leaving a somewhat triang- 

 ular orifice bounded on the external edge by this drawn curtain 

 and on the median edge by the rounded rim against which the 

 curtain comes when it is closed. Deep inside the large orifice 

 opens the smaller oviduct tube full of eggs, each filling the tube 

 from side to side. These eggs are also fixed by the heat in some- 

 thing of their natural irregular form. In life the eggs come out 

 distorted by pressure and are so soft and flowing, like liquid in 

 thin bags, that they mutually flatten against one another and 

 become indented by contact with solid objects. 



The eggs generally emerged in two streams one from each ovi- 

 duct, but in some cases only one oviduct was used for a long time. 

 The rate at which the eggs came out varied from 12 to 60 a minute 

 on each side. With some stoppages and changes in speed some 

 two to six hundred eggs were laid, by different females, in less 

 than half an hour. Frequently the eggs came out in sets of three 

 flattened together and the last one of the set rounded itself off 

 during the brief pause before it was pushed away by the coming 

 out of the next set. Thus the mouth of the oviduct was alter- 

 nately taken up with one rounded egg and with three flattened 

 eggs. When the end of deposition drew near, a gradual ending 

 was brought about in one case by a cessation of all flow for two 

 minutes and then the emergence of only two eggs, the last to be 

 laid. When this animal was dissected an hour later the ovary 

 was empty save for three eggs in the posterior lobe and two in the 

 left oviduct and one of these slipped out of the mouth of the ovi- 



