534 THE POPULAR SCIENCE MONTHLY. 



PvECEXT VIEWS EESPECTING CANCER. 



By EOBEKT T. MOKEIS, M. D. 



WHEN one of the gall-liics {cynips) stings the tender shoot of a 

 rose-bush, the poison which is deposited along with her eggs 

 excites at that portion of the twig an excessive degree of nutrition, 

 and the resulting swelling becomes the home of the young of the fly. 



The rose-bush gall is composed of nothing more than ordinary vege- 

 table tissues ; but they are abnormally developed, and there is an ac- 

 companying modification in the growth of normal structures. For in- 

 stance, the vegetable hairs at that point may increase in size until they 

 resemble large thorns, and an involved leaflet may lose its identity and 

 become a part of the tumor. The color-grains {c]dorophyU\ which 

 should give to the bark a green color, may show various shades of red 

 instead. The rose-gall is not very difi'erent from the morbid growths 

 of animal tissues which appear as tumors of various kinds ; and we 

 know that some, and presume that many, of the latter, are due to the 

 disturbance caused by the presence of humble parasites belonging to 

 the vegetable world. These parasites, or microbes, as they are called, 

 are so small that it is impossible at present to study the life-histories 

 of some of the species. No one has satisfactorily described any spe- 

 cific cancer-producing microbe, but it was only yesterday that we be- 

 came acquainted with the cousins which cause the development of the 

 tumors of glanders, of tuberculosis, of carbuncle, and of " big-head " 

 {actinomycosis) — so that, reasoning by analogy, it seems more than 

 probable that all malignant growths belong to the infectious microbic 

 diseases, and that by to-morrow we shall have the tiny causators in a 

 position in which they can be examined. 



The malignant tumors of warm-blooded vertebrate animals are di- 

 vided into two great classes — the sarcomas and the cancers. These 

 growths are like the galls of various plants, in that they are composed 

 not of new tissues, but of abnormally arranged tissues of ordinary 

 character. Structures in their vicinity lose caste and become merged 

 into tissue of some one type, just as the leaflet gives up its position as 

 a lung for the rose and helps to build a house for the young gall-flies. 



We have in cancer a sort of anarchy of cells, as it were, in which 

 the leaders, whose work, for instance, consisted in the construction of 

 muscle, are routed from their high positions and forced to become 

 common members of a low organization. 



Like many popular names the term cancer is indefinite, but it is 

 principally used to distinguish three or four forms of malignant 

 growth from the sarcomas and from benign tumors. The benign tu- 

 mors grow within limiting capsules ; pushing other tissues out of the 

 way as they increase in size, and showing no tendency to affect the 



