1148 THE NUTEITION OF THE BABE. [BOOK iv. 



been completely thrown off, and, as was stated in 306, 

 born animals bear with impunity a deprivation of oxygen, which 

 Avould be fatal to them later on in life. 



Associated probably with these constructive labours of the 

 growing frame is the prominence of the lymphatic system. 

 Not only are the lymphatic glands largely developed and more 

 active (as is probably shewn by their tendency to disease in 

 youth), but the quantity of lymph circulation is greater than 

 in later years. Characteristic of youth is the size of the thymus 

 body, which increases up to the second year, and may then re- 

 main for a while stationary, but generally before puberty has 

 suffered a retrogressive metamorphosis, so that very often hardly 

 a vestige of it remains behind. The thyroid body is also rela- 

 tively greater in the babe than in the adult ; the spleen, on the 

 other hand, relatively to the body-weight does not change 

 greatly, though rather smaller in the adult. As we have already 

 said the recuperative power of infancy and early youth is very 

 marked. 



The quantity of urine passed, though scanty in the first 

 two days, rises, rapidly at the end of the first week, and in 

 youth the quantity of urine passed is, relatively to the body- 

 weight, larger than in adult life. This may be, at least in 

 quite early life, partly due to the more liquid nature of the 

 food, but is also in part the result of the more active metabo- 

 lism. For not only is the quantity of urine passed, but also 

 the amount of urea and of some other urinary constituents 

 excreted, relatively to the body-weight, greater in the child 

 than in the adult. The presence of uric acid, of oxalic acid, 

 and according to some, of hippuric acid in unusual quantities 

 is a frequent characteristic of the urine of children. It is 

 stated that calcic phosphates, and indeed the phosphates gen- 

 erally, are deficient, being retained in the body for the building 

 up of the osseous skeleton. 



715. It would be beyond the scope of this work to enter 

 into the psychical condition of the babe or the child, and our 

 knowledge of the details of the working of the nervous system 

 in infancy is too meagre to permit of any profitable discussion. 

 It is hardly of use to say that in the young the whole nervous 

 system is more irritable or more excitable than it is in later 

 years ; by which we probably to a great extent mean that it 

 is less rigid, less marked out into what, in preceding portions 

 of this work, we have spoken of as nervous mechanisms. In 

 new-born puppies and some other animals stimulation of the 

 various cerebral areas does not give rise to the usual localized 

 movements ; these do not appear until some time after birth ; 

 but in this respect differences are observed in different kinds of 

 animals corresponding to the well-known differences between 

 different kinds of animals in the powers possessed at birth : 



