Growth. 87 



The food gathered either by the young bird or 

 supplied to it by the mother contains the same ma- 

 terials as are found in its own body just formed from 

 the ^%%^ because Instinct guides in its selection. 

 Physiological function of the mother supplied the tg^ 

 from which the body of the young bird was formed, 

 and now her Instinct leads her to supply, through 

 volition, her young with additional substance of the 

 same kind. The Instinct of the young bird and 

 that of the mother both join to bring more material 

 within the working sphere of the same artificer that 

 first formed the bird from the materials in the ^g'g. 

 But how unlike in appearance from the substance 

 of the ^gg, are the grain and insects now supplied 

 to carry on the work ! But Instinct recognized 

 them as proper materials before chemistry was 

 known, and from these materials, that inscrutable 

 something that formed the bird within the ^'gg now 

 carries on its work to completion. It enlarges bone 

 and muscle and feather. This is growth, which at 

 first sight seems a simple matter compared with the 

 evolution of a perfect bird with all its complex tis- 

 sues and system of vessels from a single cell, but in 

 reality it is just as difficult of comprehension, or 

 rather just as far beyond our comprehension as the 

 other. The materials used we understand perfectly, 

 and the process of digestion and distribution we are 

 able to trace very fully. We see in the process the 

 action of chemical affinity and mechanical forces ; 

 but while all this knowledge is a great gain to us it 

 is not all. We no more feel that we know it all 

 now than we did before Chemistry and Physiology 



