226 CAUSES OF VARIATION 



and that under-development due to insufficient food is quite 

 distinct from dwarfing, especially among animals, in that the 

 body does not develop proportionately. In underfed calves, for 

 example, the head outgrows the rest of the body, the legs are 

 long, and the joints are large. 



In general, full feed means not only increased size but early 

 maturity as well, which is of even greater consequence. Because 

 of the large proportion of food never recovered in gain, it is 

 manifest that any shortening in the period of development re- 

 sults not only in improved quality but also in the saving of feed ; 

 in other words, early gains are economical gains and they tend 

 to higher quality. 



Effect upon fertility. The amount and character of food often 

 exert profound physiological influences. For example, the fer- 

 tility of the female honeybee is mainly due to food, the sterile 

 workers and the fertile queens developing from the same eggs. 

 If, even after the worker eggs are hatched and the larvae well 

 developed, they be taken from the worker cells, put into queen 

 cells, and fed " queen's food," they will develop into queens, 

 a fact often taken advantage of by the bees themselves when by 

 accident all the prospective queens have been lost. Here fertility 

 is largely a matter of food, although an occasional worker is 

 known to produce eggs. This general difference between worker 

 and queen must therefore be regarded as one of development 

 dependent mainly on the food supply. 



Speaking generally, excessive food supply leads to infertility 

 among both plants and animals. The former vegetate luxuri- 

 ously, but they do not blossom and fruit so abundantly as under 

 a full but moderate supply of plant food. 



Whether the effect in question is due to overfeeding or to 

 some one or two elements in particular is not well established. 

 Enough is known, however, to justify the assertion that extreme 

 proportions of nitrogen produce luxuriance in stem and leaf at 

 the expense of flower and fruit, but there is exceeding doubt 

 whether this effect would follow a well-balanced food supply 

 with plenty of phosphorus. 



Excessive feeding of animals, especially females, tends to fatty 

 degeneration of the essential sexual organs, and consequently to 



