296 BOTANICAL GAZETTE. [Nov., 
and the bottom of the tube. In other words, there may be a 
membrane covering the liquid anda deposit in the bottom, With 
reference to the liquid itself, it may remain clear or become 
clouded. In the former case the growth may appear as a mem- 
brane or a deposit, or it may be disseminated through the fluid 
in minute granules, flakes or cloud-like masses. The cloudiness 
may be very faint—a slight opalescence—or it may be dense, ap- 
proaching a turbidity. When.shaken the cloudiness may be, as 
it were, set in motion, and thus show itself composed of elements, 
indistinguishably minute, or as granular or flocculent masses; or 
it may be impossible by shaking to disturb the uniform opales- 
cence. The liquid may become colored. There may or may not 
be a membrane present. It may vary from a mere iridescent 
pellicle to a thick creamy layer. Its formation and growth should 
be carefully noted, together with its color, consistency and struc- 
ture when fully formed. The deposit may be absent, very scanty, 
or quite abundant and colored. When agitated it will rise from 
the bottom in coarse or fine flakes, as a viscid ropy mass, or as a 
fine powder. In connection with these characters it is necessary 
to take into consideration the composition and reaction of the 
culture liquid. The temperature to which the culture is exposed 
has a marked effect upon the rapidity with which these characters 
appear. The odorand reaction of the culture of a certain age are 
also valuable in many cases. 
When these various features, and many others not given above, 
are taken alone and in combination, we have for most cultures an 
almost positive means of diagnosis as well as a ready method of 
detecting contaminations, for these features are as a rule constant. 
In order to illustrate this statement I will write down a few 
features of the growth of Bacillus subtilis? in a neutralized infu- 
sion of beef to which 1 % peptone has been added. In a tem- 
perature of about 35° C, the liquid becomes opalescent in from 6 
to 8 hours. When agitated, rolling cloud-like masses are out- 
lined by a condensation of the suspended bacteria. Within 24 
hours an interlacing network, or islands of a whitish gelatinous 
deposit appear on the surface, which within another day are fused 
into a white papery membrane covering the entire surface. This 
membrane, which is not smooth, but puckered and pouched in a 
cag! way, pushes its border up the sides of the tube, resemb- 
Ing at this stage the cupof anacorn. The liquid itself gradually 
clears up in the mean time until it is quite as limpid as before 1n~ 
oculation. This clearing up of the liquid, together with the pe- 
ee ee 
Se 
, 4) This bacillus can be obtained pure at any time by boiling in a water bath, ior from Ys 
to % hour, a filtered infusion of hay comtained ina flask cdageah with cotton wool. © 
