1887 .] Dr A. B. Griffiths on Micro-Organisms. 37 
kept at a temperature of 40° C. They grew rapidly, and after four 
days formed a yellow pellicle upon the surface of the broth. 
Tubes hTos. II. and III. contained sterilised beef-broth ; and to 
the broth in each tube was added iodine (in the proportion of 1 
millogramme of iodine to 100 c.c. of broth). The tubes were then 
inoculated with Sarcina lutea from the same source as Tube Ho. I. 
Ho growths made their appearances after the elapse of twenty-eight 
days, although the tubes were kept at the most favourable tempera- 
ture for the development of this micro-organism. After the elapse 
of twenty-eight days, sterilised platinum needles were dipped into 
tubes Ho. II. and Ho, III., and the contents of four tubes containing 
sterilised nutrient agar-agar were inoculated from them. They 
remained in the incubator at 40° C. for twenty-one days, without 
any growths making their appearances in the tubes. 
Other germicidal agents were tried (in a similar manner to the 
experiments just described) upon Sarcina lutea. Amongst these 
reagents the following proved fatal to the micro-organism : — 
0*5 per cent, solution (sterilised beef broth) of potassium iodate. 
3*0 „ „ „ „ ,, salicylic acid. 
0-4 „ „ „ „ „ sodium fluosilicate. 
{h) Micrococcus prodigiosus. 
I have already shown that salicylic acid is fatal to the growth 
and multiplication of this organism (see Part I. of this paper). 
Since the above experiments were performed upon this organism I 
have tried other experiments. In the preparation of sterilised 
nutrient agar-agar (according to the well-known methods) the above 
quantities of potassium iodate, salicylic acidy and sodium lluosili- 
cate were added before filtration. After preparing a series of tubes 
containing sterilised nutrient agar-agar, with and also without the 
germicidal agent, they w^ere all inoculated (the utmost care being 
observed) from pure cultivations of Micrococcus prodigiosus 
(fig. 3, A). 
Tube Ho. I. was inoculated by means of a sterilised platinum 
wire from the potato cultivation of the micro-organism. 
After five days’ growth at 34° C. in an incubator, the 
appearance was similar to the growth in fig. 3, B. (The 
colour was crimson.) 
