28 AGE, GROWTH, AND DEATH 



milk, 1 in the hope apparently that it will postpone 

 senility, and will leave us our powers in maturity long 

 beyond that period when we at present reach the 

 fulness of our vigour, and advance the period of time 

 when the changes of the years put us out of court. 

 He regards this as an optimistic substitute for the 

 various forms of philosophy and religion which many 

 millions of people have found helpful in life, and cer- 

 tainly it is the cheapest substitute which has ever 

 been seriously proposed. 



There is another writer who, though having a Ger- 

 man name, is in reality a Russian, Professor Miihlmann. 2 

 He has another theory in regard to the fundamental 

 nature of senility. He takes such instances as that 

 which I spoke of, of respiration in connection with the 

 production of warmth in the child's body and in the 

 body of the adult, and finds that the diminution of 

 the surface in proportion to the bulk of the body is 

 characteristic of the old, and he concludes that we be 

 come old because we do not have proportionately sur- 

 face enough left. His view implies, apparently, that if 



1 " It is plain, then, that the slow intoxications that weaken the resistance of 

 the higher elements of the body may be arrested by the use of kephyr, or better 

 still of soured milk " (Metchnikoff, Nature of Man, 19x13, p. 255). 



2 Miihlmann has published several papers on old age, which contain much 

 valuable and original matter. The following may be specially cited : 



" Weitere Untersuchungen iiber die Veranderung der nervenzellen in verschie- 

 denem Alter," Arch, mikrosk. Anat., Iviii., pp. 231-247 (1901). 



" Ueber die Veranderungen der Hirngefasse in verschiedenem Alter," Arch 

 mikrosk. Anat., lix., pp. 258-269 (igor). 



His general views are presented in his memoir, Ueber die Ursache des Alters, 

 Wiesbaden, 1900, and in a short essay in the Biologisches Centralblatt, Bd, 

 XXI, pp. 814-828. 



