BY R. GREIG SMITH. 113 



the water, which was renewed weekl}' by wa}'' of a side tube, was 

 boiled and cooled before being filled into the vessel. The 

 desiccator was kept at 28'' C. for five months. At the end of 

 this time the surfaces of the blocks were scratched with a spatula, 

 but no erosion or softening could be detected in the places where 

 the culture had been placed. It is possible that the time was 

 not long enough, and that years are necessary instead of months, 

 while on the other hand the cements were not the same as that 

 with which the canal was made. However, the experiment, such 

 as it was, gave only negative information regarding the action of 

 the bacterium. 



Another line of investigation was to discover any organism 

 capable of growing in a poor medium and likely to cause cement 

 disintegration. To isolate such, a solution of asparagin (01%), 

 cement (1%) and tap water was prepared, and bottles containing 

 this medium were infected with portions of the samples and 

 incubated at 22° C. A mixed growth appeared in all the bottles, 

 especially those infected with the cement from depths of four and 

 six inches. From these other bottles were infected, and after 10 

 dsijs agar plates were prepared. The agar medium consisted of 

 washed agar with cement and asparagin, the percentages being 

 the same as those mentioned above. A third transference into 

 asparagin -cement solution appeared to exhaust the bacteria, as no 

 growth was microscopically visible after 30 days. The agar plates 

 were infected with the cultures from the cements taken at a 

 depth of four and of six inches. The former produced two kinds 

 of colony and the latter one kind. Of the three, two were 

 identical and sub-cultures which were made showed it to be 

 Vibrio denitrijicans, Sewerin. The other organism was a coccus 

 of variable size, and when stained of irregular appearance. Sub- 

 cultures showed it to be 2£tc. radiatus. When these two 

 organisms were grown upon cement blocks, as was done with 

 Bad. croceum, no disintegration of the cement could be observed 

 on the places where the culture had been placed. From this we 

 must assume that although probably capable of growing in 

 the fluid on the surfaces of the cement particles, these two 

 organisms have no disintegrating action upon cement. 

 8 



