28 Transactions of the Society. 



A question often occurs as to the danger to man of infection 

 with these highly virulent septic diseases. It may he said that in 

 general they are only infective amongst animals nearly related 

 generically. That Davaine's septicaemia in the rabhit is not 

 infective to man, has been proved, accidentally of course ; experi- 

 mentally, too, it has been shown that it is not communicable to 

 cattle, horses, or sheep. It is certainly not _ infective to dogs or 

 cats, though readily so to guinea-pigs and mice. With anthrax, 

 however, it is otherwise; that is virulently infective to man, 

 amongst whom it is known in this country as wool-sorters' disease ; 

 cattle and agricultural stock of all kinds are liable to it, as are most 

 rodents ; also dogs and cats with difficulty ; and amphibia and birds 

 under certain artificial conditions, as has lately been shown. Mouse 

 septicaemia. I have found, though others have asserted differently, 

 not to be infective to other animals, either rodents or others. 



All the circumstances of this afiection, to some of the most 

 prominent of which I have here called attention, are easily 

 accounted for on the theory of the microparasitical origin of the 

 disease, and as it appears to me on no other. As an objection to 

 this view it has been asserted that specific pathogenic micro- 

 organisms are normally present in the blood and tissues of healthy 

 animals, and that they merely develope and multiply in the patho- 

 logical or debilitated condition consequent upon inoculation with toxical 

 matter. I have found this statement to be erroneous ; the fact is 

 that septic or putrefactive bacteria, as distinguished from patho- 

 genic, are apparently normally present in the organs and tissues, 

 which they invade, and develope in the blood, after death ; to distin- 

 guish between these species is the province of microscopical obser- 

 vation. To the neglect and inaccuracy of this, which in some 

 cases is very remarkable, is due much of the obscurity which still 

 involves this subject, and has prevented the recognition of the 

 relations of these micro-organisms. 



On the discrimination of their distinctive morphological 

 characters depend some of the questions which are of fundamental 

 importance in bacterial physiology or, as the developing science has 

 been more comprehensively termed, Schizomycology. In this view 

 those engaged in investigating the subject look with warm interest 

 to any improvement in the optical powers of the Microscope.* 



* The description of this organism was illustrated by drawings sliowing the 

 relative size and lorm ol' some different species of pathogenic and septic bacteria, 

 under an amplification of 2800. Tlie large forms were drawn by the camera lucida 

 and a 1-1 Oth water-immersion objective of Messrs. P(jwell and Lealand, with an 

 eye-piece of about 3-4ths in. fjcal length used with the micrometer. 



The objective with wbicli the preparatif>n was shown was a l-20th homo- 

 geneous immersion of Powell and Leahin<l (1 'iiS N.A.) constructed specially for 

 the examinaiion of these proto-organisms, for which it is most admirably suited 

 and invaluable. 



