SPERMATOPHORES OF AMBYSTOMA PUNCTATUM. 205 



observation of the activites of the animals in the field, by means 

 of a lantern at night. Specimens of both sexes were trans- 

 ported to the laboratory and kept under observation in aquaria; 

 several males of A. punctatum, and one of A. jeffersonianum, 

 deposited masses of seminal fluid on the floor of the aquarium, 

 but nothing resembling the formation of true spermatophores 

 occurred. The largest of these masses was nearly 2 cm. long, 

 and the quantity of sperm deposited by each individual was 

 amply sufficient to form a group of spermatophores. The be- 

 havior of the sexes toward each other presented nothing that 

 could be interpreted as normal breeding behavior. 



In the pond large numbers of spermatophores were deposited, 

 and these were carefully studied, both in situ and in the labora- 

 tory; but all the specimens collected were identified, with con- 

 siderable certainty, as the product of A. punctatum. The failure 

 to solve the main problems caused me to lay my notes and draw- 

 ings aside, awaiting an opportunity to continue the investigation; 

 but the conclusive results of Wright and Allen ('09) have made 

 this unnecessary so far as regards A. punctatum. 



Identification of Species. — The fact that A. jeffersonianum 

 occurs, though less abundantly, in the same region with A. punc- 

 tatum made necessary a determination of the species of the sper- 

 matophores found. The only available method seemed to be 

 through a study of the spermatozoa. The material available 

 consisted of spermatozoa from a considerable number of individ- 

 uals of A. punctatum, taken both at Syracuse and at Ann Arbor, 

 and spermatozoa from one specimen of A. jeffersonianum, taken 

 at Syracuse. Material from each individual was fixed by a 

 variety of methods, stained, mounted and carefully measured 

 under high powers of the microscope. The average measure- 

 ments were as follows: 



Acrosome 



A . punctatum 20 /^ 



A. jeffersonianum 17 ,« 



It will be seen that the sperm of A. jeffersonianum is in general 

 shorter than that of A. punctatum. The middle piece is most 

 easily and accurately measured, and affords the readiest means 



