127 



rupted, 1st, by the development of latent causes, which are inter- 

 nal, and, 2nd, by varieties in the nature and operation of externals. 



18. Both these distinctions are highly important, but the 

 first is more particularly so, from its application to many pro. 

 cesses otherwise obscured in mystery. It is by this law that the 

 organic changes take place which are conspicuous in the several 

 stages of life; and by it the order of disease is for the most part 

 regulated. 



"\ 19. In treating of the ovunv we have found that the differen- 

 tials, whether active or pre-disponent, which serve to distinguish 

 one specimen of organic existence from another, are possessed in 

 the ovum by derivation, and are not attributable to the influence 

 of externals. The proofs of this are variously scattered in the 

 article alluded to; 1 shall not therefore refer precisely to them, 

 but merely recapitulate the two following: 1st, that with oviparous 

 animals all the ibetal processes by which the animal is identified 

 are conducted without any external material of nutrition ; and, 

 2nd, that with all viviparous animals (as well as among vegetables) 

 the characteristics of the respective species are preserved, and 

 even tendencies expressed which are peculiar to the parental stock, 

 under the influence of externals which are common to them all. 

 These proofs may also be strengthened by recurring to our princi- 

 ple of causation; but as the subject is already separately spoken 

 of, such a recapitulation seems superfluous. 



20. Every property of life which acts requires to be renewed, 

 and for its maintenance must therefore require, and find, a simili- 

 tude in the material of nutrition. 



21. But as life appears in every sphere to possess an integrity 

 by which no property has an independent fate; that is, when the 

 whole exists the whole assimilates; and when the whole has ceased 

 to be a whole no single properties are indicated to remain ; and 

 more especially as we observe that when the latent causes from 

 parental pre-disposition become active, they also are renewed 

 from a source: on these accounts it is probable that the whole life, 

 such as it is constituted by its sum of properties, passes away and 

 is renewed by assimilation : and if this is the case it follows that 

 its latent or passive properties are supported, as well as the active 

 ones, by this same process of assimilation. The argument derives 

 additional credit from the following considerations, namely, 



22. That properties of pre-disposition conferred on the 

 ovum, and which for years have remained latent, do when they 

 are become active find their similitudes in the common material of 

 nutrition, and are perpetuated by assimilation: such is the case at 

 the period of puberty, when a peculiar secretion is produced by 

 the agency of life from glands which never secreted before; and 

 the faculty t)f this secretion, obeying all the other laws to which 

 life is subjected, acts and is renewed with considerable duration. 



23. Hence the terms of the continuance of a pre-disposing 

 property with the general constitution of the principle of life, 



