314 



THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



splenic fever, they are invariable concomitants ; 

 and being engendered in diseased parts and fluids 

 they may thereafter themselves act either as real 

 contagia or as carriers of contagion. 



The causal conditions capable of inducing 

 fermentation in the beet-root and the potato, and 

 with it the appearance of Bacteria in swarms 

 throughout their tissues, are known, and have no 

 ordinary connection with preexisting Bacteria. 

 And similarly the causal conditions capable of 

 inducing relapsing fever and splenic fever, though 

 not so definitely known, may nevertheless have 

 no ordinary connection with preexisting Spirilla 

 and Bacilli resembling those which appear in the 

 blood or tissues of the patients suffering from 

 either of these diseases. 



Thus the mere fact that in certain zymotic 

 diseases living organisms have been proved to 

 appear, affords of itself no support whatever to 

 an exclusive germ-theory, as I shall, after this 

 digression, endeavor to show. 



The fact may be quite otherwise explained, 

 either (1) in accordance with the views of certain 

 germ-theorists, though these are in direct oppo- 

 sition to the statements of others of the same 

 party ; (2) in accordance with the statements of 

 this second section of the germ-theorists, sup- 

 plemented by a belief in heterogenesis : 



1. The presence of latent germs of common 

 though modifiable ferment-organisms throughout 

 the body is invoked by one section of the germ- 

 theorists, who contend that certain altered states 

 of health, together with altered vitality of tissues, 

 may rouse such hitherto latent common organ- 

 isms into activity, and occasionally convert them 

 into so-calied " specific " forms capable of new 

 actions. But based as this view is upon wholly 

 insufficient evidence, and with its fundamental 

 position denied by other leading germ-theorists, 

 it would, eveD had it been securely founded, be 

 quite inadequate to meet the necessities of their 

 position. A special zymotic disease, which had 

 arisen in the manner above indicated, would as- 

 suredly have had what is termed a de novo origin 

 — it would have started from no specific cause, 

 and would never have developed, but for the 

 existence of those "determining conditions" 

 which brought about the altered state of health 

 and tissues. This group of conditions would 

 therefore constitute the cause of the disease; 

 and inasmuch as, by the hypothesis we are now 

 considering, the common germs are held to be 

 ever present and unavoidable, any changes or de- 

 velopments which they might take on could only 

 be studied in the same rank and side bv side with 



those of the other tissue elements — that is, as 

 consequences or phenomena of the disease. 



2. It was originally affirmed by Prof. Burdon- 

 Sanderson, 1 and it has of late been distinctly 

 reasserted by M. Pasteur, 2 that the blood and in- 

 ternal tissues of healthy animals and of man are 

 entirely free from ferment-organisms or their 

 germs. Some have sought to modify this view, 

 on the strength of certain experiments which are 

 so extremely inconclusive as to make it almost 

 puerile to have brought them forward. 3 



For, however strong the evidence is that 

 living units may, on certain occasions, be even 

 proved experimentally to appear in fluids in 

 which no living matter previously existed (arche- 

 biosis), it is even stronger to show that, under 

 certain conditions, similar low, independent forms 

 of life may originate in the midst of living tissues 

 previously free from them, by a kind of trans- 

 formation (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 favor of this last kind of 

 change may be regarded wholly apart from that 

 furnished by the closed-flask experiments, from 

 which it is quite distinct. It suffices, I thick, 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 

 originate de novo (as well as by contagion), and 

 that the organisms which characterize them are, 

 in such cases, consequences or concomitant prod- 

 ucts, not causes of the local or general condi- 



1 " Thirteenth Eeport ol the Medical Officer of the 

 Privy Council." 



2 Comptes Eendus, April 30, 1877, p. 000. 



8 Cutting out portions of the internal organs of re- 

 cently-killed animals, enveloping them with super- 

 heated paraffine, and then placing them in an incuba- 

 tor at a suitable temperature to see whether germs 

 and organisms will appear, would, even if taken 

 alone, obviously permit no certain conclusion to be 

 drawn from their appearance. But the evidence relied 

 upon by Sanderson and Pasteur tends as strongly to 

 show that they are not developments of preexisting 

 germs, as certain other evidence subsequently to be 

 mentioned tends to show that they are heterogenetic 

 products ("Transactions of the Pathological Society," 

 1875, p. 267). Yet, following a now long-established 

 custom of ignoring the possibility of the heterogenetic 

 origin of Bacteria, the results of such experiments 

 are by some supposed to demonstrate the existence 

 of latent germs in an organ like the spleen, for in- 

 stance, which is wholly cut off from outside commu- 

 nication—and even when the blood itself is declared 

 to be germlcss. 



