On the Appearances, &g. By G. F. Dowdesivell. 35 



which I have above explained. In blood of the rabbit infected 

 from a fowl and similarly stained, we also obtain the same 

 apiDcarance. 



We have here an instance of the effect of different methods of 

 preparation upon the apparent characters of one and the same Micro- 

 organism, and an illustration of the necessity for studying and 

 understanding their action in comparing these bodies with the 

 descriptions and figures of others. Accurate as is the description 

 in Dr. Sternberg's text, and correct necessarily and admirable as 

 are his photographs, it would have been impossible for any one 

 however familiar with the microbe to have identified it therefrom, 

 unless he had seen it under the conditions here described ; nor 

 could any one without this experience ever conjecture that two 

 preparations made by the different methods, seen under the Micro- 

 scope, and the figures 3 and 4, were one and the same organism, 

 made from the blood of the same animal. I must add that in the 

 blood both of the fowl and the rabbit, I believe this microbe does 

 not form true spores, neither does it grow to leptothrix filaments, 

 and though in many cases the dumb-bell appearance is deceptive, 

 yet that its regular method of multiplication is by transverse fission, 

 which occurs in an early stage of development of the cells. 



Taking into consideration all the characters I have observed, 

 and here very superficially described, as also the behaviour of the 

 microbe in artificial cultivations, as far as 1 have yet been able to 

 compare the two cases, with the fact that their development is 

 exceedingly slow and uncertain in all the media that I have yet 

 tried, and that both thrive better in liquid than in solid cultiva- 

 tions, I am of opinion that the microbe of fowl cholera and that of 

 Davaine's septichfemia in rabbits are specifically the same; as also 

 probably is the microparasite described by Dr. Sternberg.* The 

 epizooty here in question, prevalent sometimes in other countries 

 to a disastrous extent, being caused by the same contagium as is 

 Davaine's septichsemia ; a microbe, the usual habitat of which is 

 septic matter (putrid blood or human saliva), shows that there is 

 no sharp distinction between epizootic, or (most probably) epide- 

 mic and septic diseases, and disposes of the assertion sometimes 

 made, that Davaine's septichaemia is " merely " an experimental 

 disease, originated in the laboratory, and having no occurrence in 

 nature. 



In this examination, and in making the drawings of the larger 



* Since this was written I have been fortunate enough to meet Dr. Steinbeig, 

 one of our American Fellows. From a conversation with him he does not app&ir 

 to consider the microbe of his form of septichsemia in rabbits identical with that 

 of Davaine's. His opinion on such subjects is entitled to the highest considera- 

 tion; but he may possibly find cause to modify it on examining preparations 

 stained by different methods. 



D 2 



