1882.] 



MICEOSCOPICAL JOUE^^AL. 



125 



with virus, hermetically sealed, and 

 placed for a quarter of an hour in 

 water of this temperature. Here there 

 was no chance for any constituent to 

 escape, and the dead organisms might 

 be introduced into the inoculation- 

 punctures with whatever chemical 

 products there might be adhering to 

 them. Now, what is the result of in- 

 oculations with virus treated in this 

 way ? Experiment shows that a mil- 

 lion times as much as produced death 

 before, is now unable to cause the 

 least sign of disease. The liquid is 

 no longer capable of producing the 

 affection. 



Still", our opponents may maintain 

 the demonstration more or less im- 

 perfect — the activity of the virus is 

 destroyed at this low temperature, it 

 is true, but what evidence have we 

 that the bacteria were destroyed 

 rather than the other agents which 

 we have supposed might constitute 

 the active principle. Some bacteria 

 resist a boiling temperature for a 

 longer time than this ; others multi- 

 ply rapidly and seem to enjoy a tem- 

 perature nearly thirty degrees above 

 that to which we have subjected our 

 virus. Is it not impossible that the 

 micrococci under consideration were 

 killed at so low a point ? 



The fact that this virus is destroy- 

 ed so easily, and that bacteria often 

 resist such high degrees of heat, cer- 

 tainly makes our evidence so much 

 the stronger if we can prove that the 

 micrococcci which we have cultivated 

 are actually destroyed at this point; 

 for it would be extremely improbable 

 that an accidentally introduced organ- 

 ism would be destroyed at exactly 

 the same temperature as some un- 

 known agent which was present, and 

 upon which the activity of the liquid 

 depended. 



Let us take two sets of cultivation- 

 apparatus containing sterilized liquids 

 of the proper kind, and to each of 

 these add, with suitable precautions, a 

 minute quantity of a pure cultivation 

 of the micrococci. The one we heat 

 for fifteen minutes to 131" F., the 



other to 132°, and place both in the 

 incubator to await developments. In 

 twenty-four hours the former is tur- 

 bid with micrococci, but the latter is 

 as limpid as at first; we wait for two 

 or three days but there is no change 

 in our results. We now inoculate a 

 number of fowls from each apparatus, 

 and find that in those cases where the 

 liquid containing the micrococci is 

 used the birds contract the disease 

 while those inoculated with the clear 

 liquid are not affected in the least. 



Our demonstration is now com^ 

 plete — we have started with the mi- 

 crococcus and tested each hypothesis 

 without other result than to show 

 that they are both untenable, and after 

 traversing the whole circle of investi- 

 gation we are led back to this organ- 

 ism as the pathogenic agent without 

 which in a living condition, there is 

 no virulence. 



We believe, therefore, that the sec- 

 ond step in the germ-theory is taken, 

 the second story of the structure fin- 

 ished ; and we place the results before 

 the scientific world with the fullest 

 confidence that they will be confirm- 

 ed and accepted. 



It will be noticed that many of the 

 investigations appear on their face to 

 be rather of a chemical or pathologi- 

 cal nature than microscopical, and as 

 such would be out of place in this 

 Journal. I beg leave to remind the 

 reader, however, that no one but a 

 microscopist can succeed in such re- 

 searches — the microscope is neces- 

 sary at every step, and it has been a. 

 part of my purpose to show that the 

 microscopist who undertakes to solve 

 these difficult questions, must be pre- 

 pared to use other apparatus in con- 

 nection with his instrument.* 



The Micro-organisms of Tutoer- 

 ciiiar Disease. 



BY DR. L. SCHONEY. 



In response to your request, I will 

 endeavor to bring before you this 



* My investigations have been published in 

 the Reports of the Department of Agriculture. 



