Ethel M. Doidge 67 



being auriculate-lacerate ; they are coppeiy by transmitted light, 

 creamy white to light dull, green yellow^ by reflected light. In crowded 

 plates the colonies are small and somewhat raised ; submerged colonies 

 are very small and are lenticular in outline. A greenish fluorescence 

 may always be observed from agar media on which this organism has 

 been grown ; frequently this is very marked, and in thickly sown 

 plates can be detected after 24 hours' growth. This characteristic 

 appears to vary with the composition of the medium, and the conditions 

 under which the organism is grown ; it is more marked when the 

 organism has been in cultivation for some time than when it is newly 

 isolated, and also appears to be more conspicuous in cultures which 

 have been exposed to the light ; slight variations in the composition 

 of the medium are also probably responsible in some degree for variations 

 of this kind. No crystals have been seen in old cultures. Under the 

 microscope the texture of the surface colonies is homogeneous and 

 very finely granular. 



Nutrient agar (+ 15). Streak cultures on nutrient agar are wet- 

 shining, yellowish white, flat smooth, undulate at the edges, and inclined 

 to spread over the wetter parts of the medium. No crystals are formed. 

 There is always more or less fluorescence from the agar, but, as observed 

 in connection with the plate cultures, it is variable. Sometimes there 

 is a distinct greenish fluorescence from the agar and the bacterial 

 growth at the end of 24 hours; sometimes it is not marked until the 

 culture is five or six days old ; it is more noticeable when the tubes 

 have been exposed to the light. The growth in the condensation 

 water is very viscid. 



Nutrient agar. Stab. The best growth takes place at the top. 



Dextrose agar. Streaks were also made on nutrient agar to which 

 2 % dextrose had been added. On this medium the growth was slightly 

 heavier than on ordinary nutrient agar ; it was opaque, creamy white, 

 and the medium was rendered opaque, in contrast to ordinary nutrient 

 agar which remains translucent and exhibits a greenish fluorescence. 



Hiss glucose medium, produced a very similar growth to that on 

 dextrose agar, but it was more noticeably viscid, drawing out into 

 fine threads on the platinum needle. 



Nutrient agar + 2 % dextrose and litmus. The streak is similar 

 in character to that described on nutrient agar with dextrose, but 

 striking colour changes may be observed in the medium. On the 



1 Colours are named according to Ridgway's Colour Standards and Nomenclature 

 and have been carefully compared with colour charts in that publication. 



5—2 



