CONDITIONS FAVOURING FEEMENTATION. 91 



(heterogenesis) of some of the units of protoplasm, which though 

 still living, have been modified in nature and tendency by reason 

 of their existence in a partially devitalized area. 



The evidence in favour of this last kind of change may be re- 

 garded wholly apart from that furnished by the closed-flask ex- 

 periments, from which it is quite distinct. It suflBces, I think, to 

 account for the presence of organisms in some of those local and 

 general diseases with which they are known to be associated, and 

 therefore to complete the proof that even such disease may origi- 

 nate de novo (as well as by contagion), and that the organisms which 

 characterize them are, in such cases, conseqiiences or concomitant 

 products, not causes of the local or general conditions at whose 

 bidding they appear. The elements of the proof are these : — 



(a) Eirst there is the evidence which has been adduced by various 

 observers as a result of the study by the microscop.e of the mode 

 in which organisms appear within tissue-elements. I do not lay 

 much stress upon this here, because evidence of such a nature is 

 more open to various objections than that which is to follow*. 



{h) Although the blood and internal tissues of healthy animals 

 and of man are free from independent organisms and their germs, 

 yet such organisms will habitually show themselves after death, 

 in the course of a few days, throughout all the organs of one of 

 the lower animals or of man — even when life has been abruptly 

 terminated during a state of health. It cannot be said, in explana- 

 tion of this, that the organisms naturally present in the intestinal 

 canal have been enabled to spread through the body so as to reach 

 its inmost recesses after death — since many of the organisms 

 found are motionless, and others have mere to-and-fro movements 

 of a non-progressive character. The blood, again, has ceased to 

 circulate, so that this fluid, germless during life, cannot after 

 death be considered to act even as a carrier. If the organisms 

 themselves cannot make their way through the tissues, and if no 

 carrier exist, they must naturally have been born in or near the 

 sites in which they are found. 



Phenomena of this kind are to be witnessed even in insects, 

 such as silkworms and flies ; and the organisms that habitually 

 develope in them after death are, as in the case of higher animals, 

 just such organisms as appear in some of their best-known con- 

 tagious diseasesf. Certain of these diseases, like " muscardine," 



* On this subject see ' Beginnings of Life,' vol. ii. p. 342. 



t Ibid, pp.327, note 1, and 330, and Trans, of the Patholog. Soc. 1875, p. 343. 



