GENERAL CONSIDERATIONS. 369 



gradually desquamated, and, when once formed, do not pass 

 through any further changes. An attempt has been made 

 by Dr. Beale to distinguish in all the tissues a matter en- 

 dowed with the so-called vital properties, which he calls ger- 

 minal matter, and a "formed material," which is passive and 

 cannot become the seat of vital actions. 1 Under this idea, 

 the functions of nutrition and development are performed ex- 

 clusively by germinal matter. This theory has been adopted 

 by few physiologists ; and we cannot but regard such a divi- 

 sion as purely anatomical and artificial, as far as the 

 physiology of nutrition is concerned. It is hardly more 

 than a new statement of the old idea of the activity of the 

 nucleus in the process of cell-development. TVe are not 

 called upon to enter into an extended discussion of this ques- 

 tion, until some facts are brought forward which would 

 render such an hypothesis probable. 



The whole question of the essence and nature of the 

 nutritive property or force resolves itself into vitality. Life 

 is always attended with what we know as the phenomena of 

 nutrition, and nutrition does not exist except in living organ- 

 isms. When we can state positively what is life, we will 

 know something of nutrition. At present, physiologists 

 have only been able to define life by a recital of certain of 

 its invariable and characteristic attendant conditions ; and 

 yet there are few, if any, definitions of life regarding it as 

 the sum of the phenomena peculiar to living organisms that 

 are not open to grave objections. 



If we regard life as a principle, it stands in the relation 

 of a cause to the vital phenomena ; if we regard it as the 

 totality of these phenomena, it is an effect. 



If we study the development of a fecundated ovum, life 

 seems to be a principle, giving the wonderful property 

 of appropriating matter from without, until the germ be- 

 comes changed, from a globule of microscopic size and an 



1 TODD, BOWMAN, AND BEALE, The Physiological Anatomy and Physiology of 

 Man, London, 1866, p. 87. 

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