94 



INDUCED BREEDING 



APftjL 



INTERSTITIAL s 

 TISSUE i"^ 



THUMB PAD 5° 



MAY 



JUNE JULY 



AUO 



SEPT OCT 



NOV DEC- MARCH 



MATURATION « 



NORMAL CYCLIC CHANGES IN PRIMARY a SECONDARY 

 SEXUAL CHARACTERS IN THE FROG, RANA PIPIENS 



Glass & Rugh 1944: Jour. Morph. 74:409 



Artificial fertilization : Male frogs need not be injected with the pituitary 

 hormone unless it is desired to show amplexus. In this case, inject the male 

 at the same time the female is injected, with the same dose of pituitary 

 glands, and place them together in the same container. Amplexus, at lab- 

 oratory temperatures, will be achieved in about 24 hours and fertilized eggs 

 will be layed in the aquarium, generally early in the morning. Use water in 

 which embryos are known to develop. 



From September until April mature, functional spermatozoa can be secured 

 from Rana pipiens males of body length of more than 70 mm. simply be dis- 

 secting the testes in Spring or Pond Water, or any medium in which they are 

 known to be viable. Generally two pairs of testes are dissected in about 10 

 cc. of water and are allowed to stand for 5-10 minutes at laboratory temper- 

 atures in order to allow the spermatozoa to become active. 



