26 Transactions of the Society. 



11.-0)1 a Minute Form of Parasitical Protophyte. 

 By G. F. DowDESWELL, M.A., F.E.M.S. 



{Read lUh December, 1882.) 



OuK knowledge of the minute forms of proto-organisms— pathogenic 

 Bacteria, as they are frequently termed — which in some cases 

 have been shown to be the cause, constituting the contagium, of 

 infective diseases, has been greatly extended by recent advances in 

 optical science, together with improved methods of preparation, 

 and their presence has now been demonstrated where previously 

 it was but suspected. Where recognized they were mentioned 

 under general terms, without it being practicable to describe the 

 characters w^hich distinguished one ibrm or species from another ; 

 whereas now we are often al)le closely to examine and measure 

 some of the forms so as readily to discriminate and define them. 

 There are others, however, so minute as to tax our best c sources : 

 such is the microphyte now offered to notice. 



The preparation in which it is shown is a section of the 

 lung of a mouse infected with a form of septicaemia, in which 

 this organism appears to constitute the contagium. From a micro- 

 scopical point of view a principal feature of interest here lies in 

 the circumstance of its ultra-minute size, being, I believe, the 

 most minute independent organism yet described. 



The specific characters of this disease have been described by 

 Dr. Koch in Germany * and by myself in this country.f It has 

 not been observed to occur spontaneously, though there is every 

 probability that it does so, inasmuch as the contagium in this case 

 unquestionably originates in contamination from the atmosphere, 

 and it is a significant fact that specific infection, or in other words, 

 the occurrence of this organism in the putrid blood used for 

 inoculation, is far more uncertain and rare in the winter months 

 than in the summer and autumn. This is accounted for by the 

 fact that the lower fungi or their germs are far more abundant in 

 the air in summer than in winter. 



In the section of lung shown occurs a large vein, in longi- 

 tudinal section, in which amongst the red blood-corpuscles,t which 

 are well preserved by absolute alcohol, there are seen several 

 deeply stained round cells ; these are the white corpuscles of the 

 blood, somewhat swollen, and filled in varying numbers with the 

 minute parasite here in question — in some, where not too crowded, 

 they can be distinctly resolved ; on the inner walls of the vessel too 



* Untersuch. iib. d. ^tiol. d. Wundiiifections-krankheiten. Leipzig, 1878. 



t Quart. Jnurn. Micr. Sci., xxii. (1882) p. (JO. 



X Tlieir diametiii is about l-4000th in , tliote of num being l-3200th in. 



