598 OF NUTRITION. 



material is supplied ; thus there seems to be a complete stoppage of this action 

 in Fever, and a diminution of it in that irritable state of the system, which 

 results from excessive and prolonged bodily exertion or anxiety of mind, es-* 

 pecially when accompanied by want of sleep. It is difficult to separate this 

 cause, however, from mal-assimilation on the one hand, or from too rapid 

 decay of the tissues on the other : for we know that, in such states, there is a 

 tendency to imperfect elaboration of the Fibrinous element, and at the same 

 time an unusually rapid disintegration, as manifested by the increased amount 

 of Urea in the urine. The influence of excessive waste in causing Atrophy 

 of the body, is well shown in the cases of Diabetes mellitus and colliquative 

 Diarrhoea ; in both these, the increase and depravation of the secretions are 

 undoubtedly to be regarded as the effects, and not the causes, of the textural 

 changes with which they are associated. Colliquative Diarrhoea is a constant 

 occurrence on the last day or two of life, in animals reduced by Starvation ; 

 and is accompanied by that foetid odour of the body, which indicates that 

 decomposition is already going on throughout the system. The same thing 

 occurs as the ordinary termination to many diseases of exhaustion ; in which 

 Inanition is unquestionably the immediate cause of death. 



790. Partial Atrophy may occur in consequence of disuse of the organ 

 affected, occasioning inactivity in its formative processes; or as a result of a 

 deficiency of nutriment, occasioned by an obstruction to the circulation. Of 

 the operation of the former cause, we have many examples in the ordinary 

 processes of the economy. Thus the Uterus is atrophied, relatively to its 

 previous condition, as soon as parturition has taken place ; and the Mammary 

 glands, when lactation has been discontinued. It is probably in part to this 

 cause, and in part to the diversion of the blood into other channels, that we 

 are to attribute the atrophy of many parts, as the development of the system 

 advances, which at an earlier period were of large comparative size, such as 

 the Corpora Wolffiana, the Suprarenal capsules, and the Thymus gland. 

 Many instances might be adverted to, of the influence of suspension of func- 

 tional activity, as a result of disease or injury, in producing local atrophy. 

 One of the most common cases, is' the atrophy of Muscles which is conse- 

 quent upon their disuse. This disuse will produce the same effect, whether 

 it be occasioned by paralysis, which prevents the nervous centres from excit- 

 ing the muscles to contraction; or by anchylosis, which interposes a mechani- 

 cal impediment to their use ; or by fractures or other accidents, the reparation 

 of which requires the limb to be kept at rest. Or even if, without having 

 suffered from any injury, a limb be fixed during some time in one posture, its 

 muscles will become atrophied, as is seen in the case of the Indian Fakirs. 

 (See 588). Similar facts may be adduced, in regard to Atrophy of Nerves, 

 from interruption of their normal function. Thus when the Cornea has been 

 rendered so opaque by accident or disease, that no light can penetrate to the 

 interior of the eye, the Retina and the Optic nerve lose, after a time, their 

 characteristic structure ; so that scarcely a trace of the peculiar globules of the 

 former, or of the nerve-tubes of the latter, can be found in them. These and 

 similar facts are readily understood, when connected by the general principle 

 formerly laid down, that every proper vital operation involves an act of 

 nutrition ; in such a manner that, whilst the vital properties of any part are 

 dependent upon its due nutrition, the amount of its nutrition will in return 

 depend upon the degree in which these properties are exercised. 



791. Partial Atrophy may depend, however, upon causes of a purely me- 

 chanical nature; such, for example, as produce an interruption of the current 

 of Blood through the part. This may result from changes in the Arteries 

 supplying it; such as ossification, or other forms of obstruction. Or it may 

 be consequent upon disease in the part itself ; as when the deposits produced 



