VARYING ACTIVITY OF THE NUTRITIVE PROCESSES. 441 



fications of thorn. The whole of this subject, however, will be more appro- 

 priately considered hereafter (chap, xvii). 1 



3. Varying Activity of the Nutritive Processes. Separative Operations. 



354. Without any change in the character of the Nutritive processes, there 

 may be considerable variations in their degree of activity; and this, as re- 

 gards either the entire organism, or individual parts, though most commonly 

 the latter. These variations may be so considerable as to constitute Disease; 

 though there are some which take place as part of the regular series of 

 Physiological phenomena. Thus, as we have seen, it is to the excess of 

 formative activity, that the increase of the organism in the earlier period of 

 life is due, its "waste" being at the same time extremely rapid ; whilst it is 

 to a corresponding reduction in the regenerative power, and not to positive 

 excess of " waste" or decay (this, indeed, taking place very slowly), that the 

 gradual decline of the organism in advancing years is to be attributed. So 

 also we find that local as well as general variations may take place, as a 

 part of the regular series of vital phenomena ; and this during the period of 

 adult life, as well as in the earlier and later epochs. Thus all those differ- 

 ences in the proportional development of the several parts of the organism, 

 which mark the distinction between the adult and the child, even where (as 

 in the case of a dwarf) there is no difference in stature, result from a decline 

 in the formative capacity of those which are peculiarly adapted to the wants 

 of the earlier stage (the Thymus Gland, for example), and from an increased 

 activity of nutrition in those which are destined to the use of the adult, the 

 Generative organs more particularly. And the intermittent activity of the 

 sexual apparatus of the female affords a remarkable example of the same 

 principle ; this being marked, not merely in the enormous development of 

 the uterus and mammary glands as a consequence of conception, but in the 

 periodical change which takes place in the ovaries, whereby the ova are ma- 

 tured and thrown off at certain regular intervals. The decline in the forma- 

 tive power of these same organs, moreover, when as yet the organism in 

 general shows but little indication of deterioration, is another characteristic 

 example of the variation in Nutritive activity resulting from the inherent 

 endowments of the part, and essentially irrespective of the condition of the 

 blood, of the circulation, and of the organism as a whole; although, as 

 formerly shown ( 219), the production and maintenance of other and ap- 

 parently unconnected organs are complementally dependent upon the forma- 

 tive activity of the Generative apparatus. 



355. The abnormal excess of Nutritive change which properly constitutes 

 Hypertrophy, appears to depend upon a departure from one or other of the 

 conditions, under which, as already specified, the change normally takes 

 place namely, the right composition of the blood, a due supply of such 

 blood, and a proper formative capacity in the blood itself. Of the excess of 

 nutrition resulting from the presence of an excess of the peculiar materials 

 of certain tissues in the circulating fluid, examples have already been given 

 ( 330) ; it is important to remark, however, that although hypertrophy may 

 be thus induced in any of the tissues which constitute the instruments of 

 organic life, yet there is no evidence that either the Nervous or the Muscular 

 apparatus can be forced (so to speak) to an augmentation in bulk, by the 



1 In the treatment of this subject, the Author has made use of many valuable 

 illustrations contained in the first three of Mr. Paget's Lectures on Surgical Pathol- 

 ogy ; the general doctrines, however, being such as he had himself expressed ou many 

 previous occasions. 



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