130 HARRIS ON THE PIG. 



produce a given increase is almost identical. In pen 2, 

 100 Ibs. of meal produced 21.2 Ibs. of increase ; in pen 6, 

 21.3 Ibs. 



The more we study these results, the more are we im- 

 pressed with the importance of the study of physiology 

 and breeding, in connection with the chemistry of food. 

 Thus, in the same pen, on the same food, one pig gains 

 45 Ibs., and another 114. In another pen, one gains 65, 

 and another, on the same food, 143 Ibs. And so it is in 

 all our experiments on animals. There is a cause for this, 

 and we cannot but hope that the subject will receive more 

 attention from scientific investigators than they have 

 hitherto bestowed upon it. 



We should remark that, in pen 5, with Indian meal 

 alone, one of the Pigs, No. 1, during the first fortnight, 

 gained over 2 Ibs. per day, while the other two only 

 gained about half as much. Before the end of the first 

 fortnight, however, " it was observed that this fast gain- 

 ing pig, and one of the others, namely, No. 3, had largo 

 swellings on the side of their necks, and that, at the same 

 time, their breathing had become labored. 



"It was obvious," say Messrs. Lawes and Gilbert, " that 

 the Indian corn-meal alone was, in some way, a defective 

 diet ; and it occurred to us that it was comparatively poor, 

 both in nitrogen, and in mineral matter, though we were 

 inclined to suspect that it was a deficiency of the latter, 

 rather than of the former, that was the cause of the ill 

 effects produced. We were, at any rate, unwilling, so 

 far to disturb the plan of the experiments, as to increase 

 the supply of nitrogenous constituents in the food, and 

 accordingly determined to continue the food as before, 

 but at least to try the effect of putting within reach of 

 the pigs a trough of some mineral substances, of which 

 they could take if they were disposed. The mixture 

 which was prepared was as follows : 



