372 Profs. Percy Fraukland and Marshall Ward. 



At 4. P.M., after five hours' exposure, plates were made, and 

 incubated at 15 C. 



Taking the violet bacillus first. Nothing appeared on either of the 

 two plates made from the exposed tubes, although they were kept till 

 November 24, i.e., seventeen days. On the plate made from the 

 dark tube, two white colonies were visible in forty-eight hours, and 

 on the 13th i.e., after six days three colonies were seen. These 

 remained white until December 1, when one of them began to show 

 the violet line. On December 6 this was more pronounced. 



The experiment, therefore, showed negative results only, and I 

 regard it as probable that the mere immersion in water injures the 

 bacillus. On the other hand, it is possible I did not use sufficient 

 material in making the plates. 



Thus the plates of exposed tube = l/28th c.c. of 7/28 dilution, and 

 that of dark one = l/27th c.c. of 1/27 dilution, thus giving only 

 2187 per c.c. even in the unexposed tube, making it probable that the 

 last suggestion is the right one. 



Now, as regards the yellow bacillus, Colony *. Of the two plates 

 made from the insolated tube, one was contaminated, and yielded no 

 results, except that plenty of colonies appeared ; the other failed 

 utterly. The plate from the dark tube showed innumerable typical 

 colonies, and was completely liquefied on the fourth day. 



The experiments consequently must be regarded as negative. 



The plates of Colony <) behaved as follows. That from the dark 

 tube gave a typical series of colonies about 500 = 500x28x28 = 

 392,000 per c.c., softening the gelatine in two days. 



That from the lighted tube gave far fewer about 100 X 25 X 5 = 

 12,500 per c.c. colonies, and these smaller, showing evident retard- 

 ation ; otherwise no results. 



On November 12 the above experiment was repeated with Colony *, 

 Colony 7/, and the rosy-red bacillus , exactly as before. The day 

 was cold and bright, though some haze appeared after 1 P.M. Ex- 

 posure 10.30 to 3.30 as before, and thermometers = 10 12 C. 



The plates of Colony * behaved as follows. That from the dark 

 tube was liquefied by numerous colonies, which appeared on the 

 second day. On the fourth day all the gelatine was liquefied. 



The plates (two) made from the insolated tube only showed slight 

 retardation, and liquefied also on the fourth day, though more slowly. 



No difference between illuminated and dark tubes could be made 

 out in the case of Colony %, except slight retardation on the plates 

 from the former. 



The results with Colony S were still more indecisive, and I could 

 not draw any conclusions as to distinct light action. 



It appears probable that considerable differences will be found 

 between the various forms in this respect. 



