244 Ellis.- — The Life-history of Bacillus hirtus. 
days the threads had somewhat lengthened, thus showing signs of a want 
of health, but a very large number were still actively motile. It is probable 
that an abundance of food-supply has acted as a deterrent to spore- 
formation within the first six to seven days, and that later it has become 
impossible owing to the abnormal amount of excreted matter consequent 
on the postponement of spore-formation beyond the normal three days. 
The constant characteristics are (i) formation of pellicle, (2) strong acid 
reaction, the reaction in this culture being stronger than that in No. I. 
The growth in No. Ill is weaker than in Nos. O and I, evidently because 
the organism has to obtain its carbonaceous as well as its nitrogenous 
supply from the peptone, so that it evidently suffers from a disadvantage. 
When examined after eight days, the colourless nutrient medium had 
become turbid with a large number of suspended particles in solution. As 
was the case with the others, a pellicle was formed on the top. Spore- 
formation was wanting and there was a precipitate at the bottom, only in 
this case the precipitate was somewhat gelatinous in appearance. The 
culture showed, as was to be expected, a tendency to form long filaments, 
apparently as before, due to the fact that whereas the organism has sufficient 
energy to extend in length, it had not sufficient to carry out the process of 
division. When, however, short cells had been formed, these were invariably 
motile. The reaction was strongly alkaline, which should be a good 
diagnostic for the identification of this species. The constant characteristics 
are (1) formation of pellicle ; (2) gelatinous precipitate ; (3) strong 
alkaline reaction. 
The growth in No. VI is similar to that in Nos. O and I. Here also 
we see a tendency to form filaments, an absence of spores, a pellicle on the 
surface, a slight sediment at the bottom and a turbidity in the liquid. The 
reaction is acid. All these which have just been mentioned are constant. 
It will be observed that the source of N in this case is ammonium 
CH.OH.COONH, 
tartrate ( | ). It will also be observed that this is the 
v CH.OH.COONH/ 
only successful medium, of those tried by me, in which the chemical composi- 
tion is known. The availability of the C cannot depend on the combination 
CH . OH, for the same combination is obtained in several of the other 
media. In others, e. g. those in which asparagin is used, we have the com- 
bination CH, which is supposed to be still better, and yet no growth has 
taken place in Nos. IV, V, Va, V/ 3 , Vy, V 8 , in all of which asparagin is 
present. As mentioned above, I do not think that the question lends 
itself to an easy explanation, and the sum total of the conditions in each 
case must be considered. 
