GONADS AS CONTROLLERS OF CHARACTERISTICS 139 



Lillie I am greatly indebted for many suggestions, abundant 

 material, and a constant interest in the problem. The results 

 agree, in some respects, with those of Steinach, but are not so 

 far reaching as might be expected. This paper contains an 

 account of the observations made on the white rat; a report of 

 similar experiments on guinea-pigs will follow later, as the obser- 

 vations are not j^et complete. 



MATERIAL EMPLOYED 



The white rat (Mus norvegicus) was used for the experiments 

 and the operative procedure described by Steinach has been 

 repeated almost exactly. It appears, however, from differences 

 to be noted later that Steinach must have employed a slightly 

 different strain of rats than those used in these experiments. 

 Animals of the same age and almost invariably of the same litter 

 were selected for the cross transplantations. The method was 

 as follows : A brother and a sister rat were etherized at the same 

 time, and after operative conditions were observed the peritoneal 

 cavity of each was opened.^ The ovary, after removal and 

 sometimes accompanied by small pieces of oviduct, was cut in 

 half with scissors to aid in the establishment of a vascular con- 

 nection. A piece was placed on either side of the midventral 

 line of the male between fascia and the abdominal musculature 

 or imbedded more deeply in the substance of the muscle. The 

 genital cord of the male was severed above the epididymis and 

 both testes removed. Pieces of these were similarily placed in 

 the body of the females and the muscle layer with peritoneum, 

 and the skin were sutured separately. Usually a slight injury 

 of the fascial layer of the external oblique muscle as well as the 

 corium of the skin was made with the point of a knife to aid in 

 the establishment of a vascular connection. 



Aside from the homoplastic transplantations with complete 

 removal of the normal gonad, some of the animals were merely 

 castrated and spayed wdthout subsequent transplantation; also, 



•^ The abdomen was shaved, treated with Lugol's iodine and alcohol, instru- 

 ments sterilized in carbolic acid solution, and the table covering, towels, gown, 

 etc., sterilized. 



THE JOIRNAL OF EXPERIMENTAL ZOOLOGY, VOL. 28, NO. 2 



