350 LECTURE XIV. 



ally observe that the swelling is not simply limited to 

 the enlargement of the existing cells, but that they divide 

 and multiply. Round about a thread, which we draw 

 through the skin, a number of young cells generally show 

 themselves as early as the second day. The same change 

 may be brought about by the application of a chemical 

 stimulus. If, for example, caustics be applied to the sur- 

 face of a part, the first thing that happens is that the 

 cells swell up and then, when the process follows a regu- 

 lar course, divide, and begin to proliferate more or less 

 abundantly. Here too we have still to deal with actions 

 which do not exhibit the slightest difference in the real 

 mode of their accomplishment, whether the part be pro- 

 vided with nerves, or destitute of them, whether it con- 

 tain vessels or not. 



Accordingly, we cannot say that any part of these 

 processes appears to be necessarily dependent upon ner- 

 vous or vascular influence, but, on the contrary, we are 

 in all these cases referred to the parts themselves. The 

 relation of the vessels is not by any means to be ex- 

 plained in the way in which it is ordinarily done ; the 

 absorption of matter into the interior of the cells is un- 

 questionably an act of the cells themselves, for we are 

 as yet acquainted with no method enabling us to pro- 

 duce this kind of proliferation in the body, by any mode 

 of experimentation, through the medium of an agency 

 primarily affecting either the nerves or the vessels. The 

 circulation may be heightened in the parts as far as it is 

 possible to heighten it, without the production of such 

 an increased nutrition of the parts as to give rise to any 

 swelling or multiplication of the elements themselves. 

 Those very experiments too upon the section of the 

 sympathetic nerve which I have already mentioned, 

 have, as is well known, proved (I myself have very fre- 

 quently performed this experiment and watched its 



