NEUTRON EFFECTS ON ANIMALS 145 



began to increase and on the 4th day had nearly reached the pre-irradiation 

 level. In order to determine whether or not this recovery of the normal 

 food consumption rate coincided with a return to normal of those gastric 

 functions responsible for the movement of food from the stomach into the 

 intestinal tract, and to determine whether the effect in increasing the solid 

 residue was of long duration, 6 additional groups of 3 rats each were used 

 as follows: 



of 



Fasted 



For 24 hours beginning immediately after completion of radiation 



At the end of the fasting period the rats were killed and the solid residues in 

 the stomachs dried and weighed. The amount of food residues in the 

 stomachs of the irradiated rats (Fig. 2B) was much greater than that in 

 the controls at the end of 24 hours (Groups TV and V) and 48 hours (Groups 

 VI and VII), At the end of 3 days (Groups \lll and IX), hoAAever, the 

 amount of solid residue was equal in the stomachs of the irradiated and 

 the control groups. This suggests that the reduced food intake of rats 

 follo^^^ng irradiation is the result of food remaining in the stomach longer 

 than it normally would and that normal consumption is resumed when the 

 stomach has recovered its normal functions. 



Residual Fluid Volume. When drinking water was withheld from the 

 animals after irradiation, the amount of fluid in the stomachs of the irradi- 

 ated animals was only slightly, but consistently, greater than the amount 

 in non-irradiated rats (Fig. 3). However, when the rats had free access 

 to water the amount of fluid in the stomachs of the irradiated rats showed 

 a large and sharp increase over the amount in the stomachs of the controls 

 after the first hour following the test meal (Fig. 3). At the end of 2| hours 

 the volume in the irradiated animals' stomachs was over twdce the amount 

 in the stomachs of the control animals. 



pH of the Gastric Juice. The average pH values found in 3 experiments 

 using the gastric fluid of 9 rats for each determination are shown in Fig. 4A. 

 There was, in general, a higher pH in the irradiated groups, although, in 

 the early samples following the test meal, the pH values were lower than 

 those from non-irradiated rats. This indicates that acid secretion in the 

 stomach is impaired by neutron radiation. 



Total Acidity. During the first H to 2 hours following the administra- 

 tion of the test meal the total acidity was slightly higher in the stomachs 

 of the irradiated animals than in the controls (Fig. 4B). This is consistent 



