HABITS OF CRYPTOBRANCHUS ALLEGHENIENSIS. 1 9 



and they did not develop. The " opaque body " previously men- 

 tioned (Smith, '06 2 ), which can be dimly seen in the photograph 

 (Fig. 5), was found to have no essential significance in the proc- 

 ess of fertilization, since it is entirely a product of the female, 

 and uniformly present in unfertilized eggs. As stated by 

 McGregor ('99), the female has no seminal receptacle. 



Tests were made in order to determine how long living sper- 

 matozoa would survive exposure to water. In seminal fluid 

 taken from the vas deferens and thoroughly mixed with water, 

 motion of the sperms, both of the shaft and the filament, con- 

 tinued for about 15 minutes. In drops of seminal fluid obtained 

 by stripping and consequently mixed with the viscid secretion of 

 the cloacal glands, the motion of the sperms continued for four 

 hours after immersion in water. 



Artificial fertilization was attempted on several occasions, always 

 with complete success. Eggs for this purpose were secured by 

 killing and cutting open ripe females. Three methods were fol- 

 lowed : (<?) "dry" fertilization — mixing eggs and milt together 

 thoroughly, then immersing in water ; (<$>) eggs and milt were 

 placed simultaneously in water, then mixed together ; (c) eggs 

 were immersed in water for a minute or two, then milt added. 

 All three methods were successful. In every case eggs not arti- 

 ficially fertilized were kept as a check; in no case did these 

 develop. Hence it was proved that the sperms are able to pene- 

 trate the egg capsule from without, and that fertilization may take 1 

 place after both eggs and sperms have been exposed to water. 



All the evidence pointed to external fertilization, and it was. 

 sought to verify this by actual observation. 



With the beginning of the breeding season a marked change- 

 took place in the behavior of the animals in their natural environ- 

 ment ; they no longer remained secluded in hiding-places under 

 rocks, but came out boldly by day, sometimes congregating in 

 droves of from six to twelve, showing a social instinct quite lacking 

 during the summer. As a rule they roamed restlessly about, 

 poking their noses into crevices under rocks, as if exploring ; 

 sometimes, however, they lay quiet in the open. Several times 

 they were observed to pile up in crevices between rocks, two or 

 three lying alongside each other, or two or more at a time try- 



