Ellis. — The Life-history of Bacillus hirtus. 243 
The following table shows the results of inoculations in these media. 
0. 
I. 
II. 
III. 
IV. 
V. 
V. 
V. 
V. 
VI. 
VII. 
VIII. 
IX. 
X. 
XI. 
+ + + 
acid 
+ + + 
acid 
not tried 
+ + 
alkaline 
0 
0 
0 
0 
0 
0 
+ + 
acid 
0 
0 
0 
0 
0 
Fischer ( 4 , p. 55) in speaking of the N and C requirements of Bacteria, 
says : — ‘ Nicht brauchbar als Kohlenstoffquelle sind Harnstoff, Oxalsaure, 
d.h. diejenigen, deren Kohlenstoff unmittelbar mit Sauerstoff verkettet ist j 
und ebenso Cyan, die Stickstoffverbindung. So hat es den Anschein, als 
ob der Kohlenstoff am brauchbarsten sei, wenn er nur mit Wasserstofif 
verbunden ist, also als CH 2 , weniger gut als CH, noch minderwertiger als 
CH.OH und gar nicht als CO und CN. Eine ganz glatte Skala hat man 
hier freilich nicht vor sich.’ 
So far as O, I, and III are concerned it is impossible to say how the 
C atom is arranged. In the others the C atom is attached in all the ways 
mentioned by Fischer, but capacity to grow in any particular medium is 
not, it seems to me, such a simple affair that it depends upon the mode of 
attachment of the C atom. The sum total of conditions must be favourable, 
and what these are we at present do not know. 
The growth on No. I affords a diagnostic property which I have never 
known to fail, though I have made a large number of cultures in this medium. 
About the third day (sometimes sooner) a white pellicle forms on the 
surface. It is composed of non-motile individuals, and when first formed is 
devoid of spores. The spore-formation, however, is only postponed. After 
six days there are still usually no spores present. In a four weeks old 
culture, however, it will be found as a general rule that spores are quite 
abundant. I have always used this medium for accelerating the motility 
of sluggish cultures, and for initiating motility in cultures which, owing to 
their previous habits (in the laboratory, not in nature), had not when 
examined a trace of motility. The cells are of normal breadth and have 
dense contents. The short threads are very actively motile, the longer ones 
less so, doubtless owing to the fact that there is more inertia to overcome. 
The appearance of some of the longer threads is shown in Fig. 15, though 
it must not be inferred that this formation of threads is a constant feature ; 
the only constant characteristics are (1) formation of pellicle, (2) acid 
reaction. 
The growth in Nutrient Medium O is naturally much similar to that 
in Nutrient Medium I. In this case there always appeared an extremely 
thick sediment at the bottom of the culture and a pellicle similar to that on 
No. I on the top. The formation of spores was very scant. After thirteen 
