100 



INDUCED BREEDING 



with mammalian extracts of the anterior pituitary hormone. Spermatophores are retained 

 for many months and (particularly with T. pyr rhogaster, the Japanese newt) the majority 

 of females will give fertile eggs almost any time (October to May). The breeding tanks 

 for Urodeles should be shallow, with facilities for their climbing out onto floating pieces 

 of wood or onto sand. Aquatic plants (Elodea) should be provided not only for aeration 

 but for the attachment of eggs. Eggs will be layed singly, in large jelly capsules, and 

 will always be attached to plants. Instead of injecting large doses of pituitary it is well to 

 inject about two female (frog) glands per day for several days since Urodele eggs are 

 constantly maturing. If the animals are well fed they may be induced to lay a few eggs 

 per day over long periods. 



Ambystoma: (mexicanum, opacum, punctatum, tigrinum) 



These species apparently do not retain their spermatophores for very long before ovula- 

 tion, hence it is generally more practical to collect the eggs in nature. Ambystoma 

 opacunn eggs are available late in September; A. punctatum and tigrinum eggs from Janu- 

 ary through May; and A. mexicanum eggs in the Spring, time variable. 



A. punctatum males will drop their spermatophores in slowly running streams or in 

 ponds during the late March rains even when the temperature may be as low as 13 C. , 

 several days prior to the migration of the females from the woods. Females captured 

 after they pick up spermatophores, but before oviposition, will lay their eggs in the lab- 

 oratory spontaneously or under pituitary stimulation. 



The eggs of A. opacum and A. punctatum are excellent for operative procedures because 

 they develop rather slowly and are very hardy. The eggs of A. tigrinum are hardy but 

 develop very rapidly, while the axolotl (A. mexicanum) eggs do not stand operative pro- 

 cedures very well. 



OBSERVATIONS AND TABULATION OF DATA: 



With each attempted induction of ovulation the following data should be recorded: 



1. Number and source of anterior pituitary glands. 



2. Physiological condition of recipient, i. e. , size, evidence of sexual maturity, 

 and extent and conditions of laboratory confinement. 



3. Temperature at which the injected female was kept. 



4. Date of injection and date or time of appearance of the first eggs within the uteri. 

 6. Percentage ovulation, determined by estimate of the volume of eggs remaining 



in the ovary after the reaction has been completed. 



