19 



that these experiments can be taken without reserve as 

 an indication of what might take place in nature. 



III. — The Bacteria present in the AHmentary Canal 

 of the Oyster. 



This research has proved of very considerable utility in 

 guarding us against errors in our subsequent infection 

 experiments, and is of further interest in demonstrating 

 the large number of cases in which the colon bacillus was 

 normally present. 



Methods. — In analysing the contents of the stomach we 

 have, in all cases, cauterised the mantle over the region of 

 the stomach and have inserted a sterilised fine glass 

 pipette and withdrawn a quantity of fluid varying from 

 -oV to iV of a cubic centimetre. The contents of the tube 

 have then been mixed with liquefied agar, ordinary gelatine 

 or sea-water gelatine and Petri dishes made. The agar 

 dishes have been incubated at 37'^C., the gelatine at 21°C. 

 to '24°C. As the figures will subsequently demonstrate 

 there is an enormous difference between the number of 

 organisms appearing upon the agar incubated at the high 

 temperature and the simple or sea- water gelatine incubated 

 at the low temperature. This heat method of separation 

 proved quite equal to, if not better than, the carbolic acid 

 or potassic iodide methods. 



Experiments. — In the first six cases examined, pre- 

 cautions were taken to ensure that the oysters were 

 especially fresh, in the other cases they were obtained 

 haphazard from the various shops (see table). 



The number of organisms taken from the stomach of 

 the oyster which could survive a temperature of ST'^C, 

 was comparatively small. In a very large proportion of 

 cases (^ to ^) the organism present was B. coli in over- 

 whelming numbers, and next in frequency were species 



