176 HETEROGENETIC ORIGIN OF 



screw-top bottle in a ten per cent, formalin solution for ten minutes. 

 It was subsequently treated in exactly the same manner as the 

 potatoes had been. After the top of the bottle had been tightly 

 screwed on, it was left on the top of the incubator at a temperature 

 of about 80° F. for seven weeks. 



On examination, at the expiration of this time, the upper two- 

 thirds of the turnip was found to be somewhat shrivelled. The 

 odour of the bottle was disagreeable and pungent, though slightly 

 aromatic and spirituous. The odour was so strong that it did not 

 seem likely the shrivelling was due to evaporation, which had 

 been caused by the screw-top not being quite air-tight. 



On section, the rather shrivelled upper two-thirds was found to 

 be much discoloured and honeycombed ; the lower third being 

 much less so. Sections were made and soaked in dilute mastzellen 

 stain ; and on examination cells here and there, not continuously, 

 but in the upper and lower portions alike, were found to be crowded 

 with very minute Bacteria, most of which took the stain only 

 slightly. In Fig. 8, A ( X 500), a large aggregate of these organisms 

 is to be seen, with others scattered about over contiguous portions 

 of the section. 



Another small turnip of the same size as the last was, on the same 

 date, after being well washed, put into a screw-top bottle and 

 placed on a small earthenware pot, in order to protect it from six 

 drachms of pure formalin which had previously been poured into 

 the bottle. The top was then tightly screwed on, and the bottle 

 was placed on the incubator, by the side of the other (at a tem- 

 perature of about 80° F.), where it remained for eight weeks : the 

 turnip being in an atmosphere saturated with formalin vapour. 



On examination this turnip was likewise found to be slightly 

 shrivelled, and it was rather soft and doughy to the touch. On 

 section the colour was almost natural except for a depth of about 

 one-third of an inch round the periphery, where it was slightly 

 discoloured, and in the centre where there was a small area about 

 one quarter of an inch in diameter which had a rather gelatinous 

 appearance. 



Two sections through this central region and its neighbourhood 

 were made, and then soaked in dilute mastzellen stain. On 

 microscopical examination they were found to contain moderately 

 large Bacteria, mostly in small groups, in a large number of the 

 cells ; though here and there large masses of Bacteria were found, 

 such as are shown in Fig. 8, B ( x 500). In many of the cells the 



