M'Weeney — On a Method of Freparing Schizomijcetes. 165 



Here is a totally different appearance. The specimen I now 

 hand round is a thrust culture of the B. tetani, an organism 

 which is a constant inhabitant of the upper layers of field and 

 garden earth. The growth along the line of inoculation is orna- 

 mented with beautiful, radiating processes, like rootlets growing 

 from a tap root, and the substratum is permeated with gas-bubbles 

 which are produced by this obligate anoerobic organism, as part of 

 its metabolism. The appearance is at once ornamental and charac- 

 teristic. We have here a culture of "Symptomatic Anthrax," which 

 is likewise an anaerobic organism ; the characters are much the same 

 as those of the tetanus culture, but there is an absence of the delicate 

 processes. It is exceedingly instructive to observe that the thickest 

 part of the growth is at the bottom of the tube, where the organism 

 is as far away from the atmosphere as the depth of the tube will 

 allow. 



Another exquisite example of the naked- eye differentiation 

 obtainable by this method is afforded by the Bacillus murisepticus, 

 or organism of mouse septicsemia, which I now hand round. The 

 bluish-gray clouds — to use Frankel's expression — surrounding the 

 inoculation thrust are distinctive of the organism. Examples 

 might be multiplied ; but I have adduced sufficient, I think, to 

 confirm my statement that Schizomycetal vegetation produced in 

 this way, and petrified, so to speak, by the closure of the tube, offers 

 instructive and characteristic appearances. It must, of course, be 

 borne in mind that there are very many species which do not lend 

 themselves readily to this mode of preparation for museum pur- 

 poses. Such are those which liquefy gelatine, and do not produce 

 very characteristic appearances in agar-agar. In these cases 

 it might be possible to fix the vegetation at a given stage, by the 

 introduction into the tube of antiseptic substances; or perhaps by 

 filling it with some gas such as H or CO2 preparatory to sealing. 

 The majority of such species are, however, sufficiently characterized 

 by their growth on potato, and other opaque substrata. 



I come now to the cultures made in the flattened vessels, which 

 I' mentioned a few moments ago. These are charged with a small 

 quantity of agar-agar, which is allowed to solidify on one of their 

 flat surfaces ; and after the usual sterilisation, they are inoculated 

 with (if possible) one germ only — or (at most) a very small number 

 of germs, by means of a platinum needle. Or, the agar-agar may 



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