BY R. GREIG-SMITH. 81 



dition of the tan-bark infusion and sodium carbonate. The gas was probaldy 

 not caused by the interaction of the tannin bodies with the sodium carbonate, for 

 certain of the tubes which failed to show growth contained no gas bubbles. And 

 as growth was necessary, it is possible that the faint acidity produced during 

 growth may have given rise to the evolution of ga-s from the added carbonate. 

 The gas bubbles disajipfared when the tubes cooled down to laboratory tempera- 

 ture. It may be that the gum dei'ived from the infusion assisted in liolding 

 the gas in the medium. Be this as it may, the colonies isolated from growths 

 that gave gas formation, failed to produce gas in the absence of bark, and we 

 may conclude that the gas in the bark-infusion tubes was due to the interaction 

 of the infusion jjIus sodium carbonate and the acid formed by the liacteria from 

 the sugar. An organism capable of fermenting saccliarose directly was the object 

 cf the investigation at the moment. 



A weaker infusion of tan-bark was made bj' adding three parts of water and 

 letting the mixture stand at 22° for two hours. It was brighter and neutral 

 and clearly contained very little tannin. Slopes of saccharose nutrient agar con- 

 taining 11, 20, 27 and 33 % of this infusion were stroked with a pure culture 

 but the growths obtained did not differ in any way from those without the in- 

 fusion . 



The strengthening of the saccharose nutrient agar by the addition of peptone, 

 asparagin or meat-extract did not lead to the production of gas by the undoubt- 

 edly pure colonies. Thus up to this point the isolation of a saccharose fermenter 

 in pure culture had not been accom])lished . 



About this time it was noted that the stack-bark, originally covered with 

 dilute sodium carbonate* had al slight covering of a white mould. This consisted 

 of a mass of aerial liyphae or eonidiophores sprouting from the surface of the 

 bark and carrying sessile or nearly sessile conidia along the length of the thread. 

 They were quite short, about 0.14 mm. in length and the conidia seemed to be 

 double and 10 ju, long when measured in air witli a Leitz No. 8 objective. When 

 immersed in water, the conidiophore measured lAfx. in diameter and the conidia 

 were oval or spindle-shaped, the latter shape being caused by a collar at one end, 

 probably the remains of a short pedicel. In size they ranged from 2.8-3.5 x 

 4-6 fi. The length proved that when noted growing in the air. the conidia were 

 in couples. The contents were granular and one rather long conidium in a 

 stained film showed a light central portion suggestive of the possibility of the 

 cell being able to divide in two. The mycelia in stained films showed as un- 

 stained threads with irregularly placed, deeply stained granules and very similar 

 to the threads noted in the films prepared from the condensed water of active 

 mixed Ijacterial cultures. 



Attempts were made to pick off the minute conidia from the bark and sow 

 them upon solid media for incubation at 60° but the results were disappointing; 

 either a strong gTowth of the inactive thermophilic rod was obtained or the 

 tubes remained sterile. Hanging drop cultivation was also without result. In- 

 creasing the acidity and the alkalinity of the media, using the condensed water 

 of an active gTowth as the infecting material, were useless for augmenting the 



* The stack-bark had been covered with Wo «;odium carbonate and kept at 

 60° for two days when the fluid was found to contain active gas formers. On the 

 fourth day the liquid was used in testing for filter passers and the residual bark was 

 half covered with N/10 soda. Four da>-s later the liquid contained gas formers, and 

 in another four days the mould was noted covering many fragments of bark. 



