68 THE EVOLUTION OF LIFE 

Bacilli, for the most part motionless, and were found 
principally in surface and deep layers of the soil, in 
Thames mud, in sewage water, in the intestines of 
many kinds of animals and in their dejecta, also in 
all samples of ensilage examined. Rabinowitsch 
and other observers have also found such organisms 
in similar sites. 
The temperatures most favourable to their growth 
were tested by our authors, with three different 
cultivating media for all the fourteen forms. Some 
crew well at temperatures ranging from 37 to 47° C. 
This was nothing new, as thirty years ago | had 
made known that Bacilli would multiply most freely 
at 50 C. in neutralised urine. But Macfadyen and 
Blaxall go on to say: ‘‘ We may, however, judging 
by our observations, take 55 to 65 C., and even to 
67° C., as an optimum temperature, both as regards 
the quickness and the amount of growth that 
occurred. It was interesting to note that in one or 
two instances a very good growth occurred at 
72°5 C., whilst in a few cases evidence of growth 
was obtained. even at 7475 Cou... At the same 
time there was no doubt about the optimum tem- 
perature being about 50 C.” Under cultivation the 
majority of the Bacilli showed a tendency to grow 
in long chains. Only two out of the fourteen forms 
showed undoubted motility, though many of them 
developed ‘“ spores ”—bodies about which, in other 
Bacilli, we shall have much to say presently. 
Many of these thermophilic organisms were 
capable of growth through a remarkable range of 
temperature, though certainly many of them, outside 
