140 CARL R. MOORE 



several cases of homoplastic transplantation were made in 

 which the normal gonad remained undisturbed. Parts of fifteen 

 to eighteen litters were used in the experiments, comprising 

 over fifty operated animals. All cases of grafting were not suc- 

 cessful, and a few animals died before their mature cond'tion 

 could be studied, but the successful cases were sufficiently dis- 

 tributed to afford a wide range of conditions for study. It has 

 seemed advisable to give in detail the history of one litter and 

 allow this to serve as an example of the general conditions in 

 such experiments. This litter fulfills very adequately the con- 

 ditions sought from the fact that the transplanted gonad ob- 

 tained vascular connections and persisted in each operated 

 animal. Furthermore, there is need for constant comparisons 

 between operated animals and the normal ones under similar 

 conditions. The one litter eliminates such ordinary differences 

 as age, number of rats in litter, age of mother, hardiness, etc., 

 and since the conditions are the same separate histories will not 

 have to be repeated. 



The litter (no. 6, AIBI) was born September 22, 1917, and 

 consisted of four males and six females. Operations were carried 

 out at the age of 25, 28, and 35 days, and all were cases of homo- 

 plastic transplantation with complete removal of the normal 

 gonad, i.e., ovaries were removed and pieces of testis placed sub- 

 cutaneously and vice versa. Of the ten rats in the litter trans- 

 plantations were made on three males and four females ; unfortu- 

 nately, however, one female escaped from the cage within three 

 days after operating, which left three castrated males containing 

 transplanted ovaries and three spayed females containing trans- 

 planted testis, one normal male and two normal females as 

 controls. On November 12, 1917 (51 days old) these were 

 so marked that each one could be recognized and each was then 

 given a number making possible a complete and separate record 

 of each individual rat during the course of the experiment; the 

 experiment was terminated June 3, 1918, at the age of 254 days. 

 At that time the rats were killed and the grafts preserved for 

 cytological study. Since the different rats will be treated in- 

 dividually, the following numbers will serve to identify them: 



