14 



MASS. EXPERIMENT STATION BULLETIN 331 



P oar - n/g/i Nutrition 

 f\ ge - 8 f ds. ys 



I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I LI I 1 I I I I I I I i i .„ 

 37 35 30 2.5 £0 10 25 30 35 37 C 



jjoar - /7/g/i Nutrition 

 f\ge -105 days 



1 ii 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 i i 1 1 1 1 1 1 1 i n 1 1 1 1 1 1 l 1 1 1 11 



37 35 30 25 2.0 £0 25 30 35 37 C 



Figure 27. Kymograph Records Showing the Development of Sensitivity to Temperature 

 Changes in the Tunica Dartos Muscle of the Boar 



(High Nutrition — Normal.) 



Records were taken on isolated muscle strips. Time is in one-minute intervals on the 

 base line, and temperatures are recorded in °C. 



Low Nutrition 



In an earlier section a series of boar pigs that were fed on a low plane of 

 nutrition is described. Records were made of the reactions of strips of the 

 tunica dartos from these boars at the time of castration. The altitudes of con- 

 tractions observed in strips of tissue from these animals are given in Table 9, 

 along with figures from litter-mate controls fed on a high plane of nutrition. 

 Three of the records of the low-nutrition group are shown in Figure 28. 



The figures show that the tunica dartos had not developed as much in the 

 low-nutrition group at 105 days and over as it had in the high-nutrition group. 

 The development of the testes was also retarded, as already noted. Since the 

 tunica dartos seems to depend upon the testicular hormone for its development, 



