MODIFICATION OF THE GERM-CELLS IN MAMMALS 135 



companion on the left is a normal animal, No. 150 cf, being 4 

 years and 3 months old when photographed. The sober exist- 

 ence of this male has not given him any advantage in appear- 

 ance over the old alcoholic; both are very good males, each 

 weighing almost 900 grams when photographed. This is well 

 above the weight of the ordinary adult guinea-pig. 



Figures 2 and 3 show again on the left the same normal animal, 

 No. 150 d', in order that the reader may obtain a more definite 

 impression of the uniformly good condition of the three alco- 

 holic males. The alcoholic male No. 72 on the right in figure 

 2 was 5 years, 1 month and 10 days old when photographed. 



Fig. 1 The animal on the left is a normal male, No. 150, over four years 

 old. The one on the right. No. 80 d^, is almost five years old and had been 

 treated with the fumes of alcohol six times per week for four years and two 

 months, yet is seen to be in a vigorous condition. 



weighing over 900 grams. He had been treated with alcohol 

 fumes one hour per day until the last seven months, when he 

 was treated two hours per day for six days per week. The 

 entire duration of his treatment when photographed was four 

 years, two months and five days. 



Figure 3 shows on the right alcoholic male No. 70. This 

 animal was 5 years, 1 month and 11 days old when photo- 

 graphed, and weighed 885 grams when 5 years old. He had re- 

 ceived the same amount of alcohol treatment as the other two. 

 The three were bred and reared in our colony and are above 

 the average male guinea-pig in size and vigor. They have been 

 good breeders as young normal specimens, as well as during 



