756 



NUTRITION. 



are less abnormal, vary less from these struc- 

 tures, and more resemble either hypertrophy or 

 euplastic deposits; and they do mischief rather 

 from their size and situation than from their 

 intrinsic nature. Where the mode of growth 

 is more peculiar, and more independent of that 

 of the textures in which they arise, the resulting 

 tumours are more abnormal in their nature and 

 mode of developement; they approach in 

 character to malignant diseases, acting inju- 

 riously, not only by their bulk and position, 

 but also by abstracting the nourishment of the 

 body, and tending to supersede the natural 

 structures."* 



Among the malignant growths, too, there 

 are various shades or degrees of malignancy ; 

 one or more of the characters just now assigned 

 to them being either absent or imperfectly de- 

 veloped. Thus there are certain growths which 

 have a tendency to spread through the system, 

 and even to propagate themselves from one 

 individual to another, and which agree with 

 true malignant growths in being composed, 

 like them, of cells having a tendency to rapid 

 multiplication, but which yet exert no serious 

 influence upon the general constitutional state, 

 and which cannot, therefore, be properly termed 

 malignant : such are molluscum and porrigo 

 favoi>a. And in other instances we meet with 

 large tumours, producing a very injurious effect 

 upon the surrounding textures, and exerting a 

 very serious influence upon the system at large ; 

 the malignancy of which, however, is doubtful, 

 because they show no tendency to reappear in 

 other parts of the body. The origin of all these 

 growths is involved in great obscurity ; but 

 there does not appear to the writer to be any- 

 thing so specific in their character as to require 

 the supposition that their germs are introduced 

 into the body from without. It is true that 

 when they have once established themselves 

 they may be propagated by inoculation, which 

 transplants some of the cells or cell-germs into 

 a new locality; and the appearance of the dis- 

 ease in parts of the same body distant from 

 those which were first affected, is probably due 

 to the diffusion of the germs by the current of 

 the circulation. But this power of reproduc- 

 tion is by no means limited to malignant 

 growths, since it belongs to all cells at a cer- 

 tain stage of their developement. And, as Dr. 

 W. Buddf has remarked, the causes which 

 have been supposed to induce cancer are not 

 such as can, in any intelligible way, favour the 

 introduction of germs from without the body. 

 Thus in chimney-sweeps and others the conti- 

 nued application of soot has been observed to 

 be followed by the occurrence of cancer in the 

 scrotum in such a number of cases, as to justify 

 the inference that it has been the exciting cause; 

 and the often-repeated contact of a tobacco-pipe 

 with the lip has also been considered a cause 

 of cancer of that part. But neither of these 

 causes can in any conceivable way promote the 

 developement of cancer from extrinsic germs. 

 We are quite in the dark, however, as to the 



" Williams's Principles of Medicine, $ 574. 

 t Lancet, May 28, 1842. 



mode in which any perversion of the ordinary 

 nutritive processes arising from external irrita- 

 tion of whatever kind, can give rise to struc- 

 tures so peculiar in their nature and history as 

 are the various forms of cancerous growths. 

 For a detailed account of their characters as 

 unveiled by recent microscopic researches, the 

 reader must seek elsewhere ; since all that we 

 can here attempt is to give a general idea of their 

 peculiar nature. (See PRODUCTS, MORBID.) 

 The greater part of every true malignant growth 

 is made up of cells, which, instead of under- 

 going transformation into other kinds of tissue, 

 continue in their original state, and enjoy the 

 power of rapid multiplication. In the harder 

 forms of cancer the masses of cells are traversed 

 by bands of solid fibrous texture, and such are 

 of slow growth, and may remain with but little 

 change for many years, apparently because the 

 pressure to which they are subjected prevents 

 their rapid increase. But the softer forms are 

 composed almost entirely of cells, and these 

 of the most rapidly multiplying character; so 

 that, in the rapidity with which they shoot up, 

 they remind us of the vegetable fungi. Now 

 the influence of either of these forms of morbid 

 growth upon the constitution is very decided, 

 and distinguishes them from non-malignant 

 structures ; but this is more evident, the more 

 time is afforded for the manifestation of their 

 effects. It is evident even from the appearance 

 of the subject of them that the blood must be 

 in a very depraved state, for there is a peculiar 

 dirty sallowness about the complexion which 

 is seen in no other disease; the emaciation 

 reaches a point unequalled under any other 

 circumstances ; and accidental injuries which 

 may occur during the progress of the malady 

 are but very imperfectly repaired. In their de- 

 leterious effects upon the character of the circu- 

 lating fluid, therefore, we may not improperly 

 compare cancer-cells with pus-globules. 



General summary. From what has been 

 stated it appears evident, that the process of 

 nutrition essentially consists in the growth of 

 the individual cells composing the fabric; and 

 that these derive their support from the organic 

 compounds with which they are supplied by 

 the blood, just as the cells composing the sim- 

 plest plants derive theirs from the inorganic 

 elements which surround them. And as diffe- 

 rent species of the latter select and combine 

 these in such modes and proportions as to give 

 rise to organisms of very diversified forms and 

 properties, so is it easily intelligible that the 

 different parts of the fabric of tiie highest ani- 

 mals, whether normal or abnormal, should 

 exercise a similar selective power, in regard to 

 the materials with which the blood supplies 

 them. The structure composing every separate 

 portion of the body has what may be termed 

 a special or elective affinity for some particular 

 constituents of the blood; causing it to abstract 

 from that fluid and to convert into its own 

 substance certain of its elements : and this is 

 exercised not only in regard to the normal con- 

 stituents of the blood, but also towards morbid 

 matters which may be circulating with it. Of 

 the causes which enable the cells of animal or 



