Oil Muscular Motion and Animal Spirits 2^2) 



cerebellum and the nerves arising from it only gently 

 and with a constantly even flow ; particularly in the 

 uterus, where, namely, the infant does not yet exercise 

 the respiratory organs. Whence it comes that the 

 spleen cannot be of any use, in so far, that is to 

 say, as the nitro-aerial particles traversing the cere- 

 bellum in a slender stream are almost all required 

 for the natural functions : but when the animal has 

 grown up and exercised itself in violent labours, it is 

 necessary that these nitro-aerial particles should be 

 transmitted through the cerebellum in greater 

 abundance, so that the nitro-aerial spirits may now 

 make for themselves sufficiently open channels in the 

 cerebellum, and that the structure of the brain may 

 become more compact and firm, and so the nitro- 

 aerial particles in the future may more easily and in 

 fuller rush pass through the brain and the nerves 

 arising from it. But when these are not all required 

 for carrying on in the usual way the natural functions, 

 it is most necessary that the superabundance of nitro- 

 aerial particles should be discharged into the mass of 

 the blood and most intimately mixed with it by 

 means of some organ, such as the spleen. 



I add, besides, that while the foetus is in the uterus, 

 the viscera devoted to the digestion of food have 

 either nothing to do, or at all events act very remissly. 

 Whence it happens that the nitro-aerial spirits do 

 not go at all to these viscera, or at all events only in 

 very small amount ; and there is thus no need that 

 any part of them should be diverted to the spleen. 

 Further, as the infant immediately after birth takes 

 food continuously, or at all events at frequently 

 repeated times, so that its stomach is to some extent 

 filled with food, and consequently the nitro-aerial 

 spirits ought to come to the viscera devoted to 



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