176 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
evolution towards A, must necessarily pass through the forms which are shewn as 4A and 
4B ; it may be that the mycelium-like growth and the diverse forms of 4A are rather 
involution-like forms of B than an essential stage in its development. With regard 
to stage 2, I have been unable up to the present, to decide it with certainty. In the 
description of type A, a process has been given in detail, which is to be observed in 
pflucose broth cultures, which results in the extrusion of minute granular forms from 
the A forms. As has been already stated, this granule growth has not been seen in 
these cultures to develop to more than a very limited extent, and in the great majority 
of cases , no colonies develop, except colonies of A, when such cultures are plated. 
The two exceptions have also been related. Under the circumstances, I am not able 
to state that this process ot dehiscence and extrusion is a real phase in the life history 
of the organism, and the question must be left for further study. 
In my previous paper I described a process of sporulation to which I have 
referred in Chapter I of this paper. In the series ot observations which I am now 
reporting I have not seen this process with the same clearness, but the process of 
dehiscence and granule extrusion resembles it, though it does not reproduce all its 
characteristics. Therefore, although there is evidence pointing to the fact that stage 
two is represented by a spore-producing form, yet for the present this is inconclusive. 
In the last place, I wish to refer back to the statement above, that the cultures of 
type B which obtained from the tumours are identical in character with those of type 
B obtained from the lesions produced in animals by the inoculation of type A. This 
statement is based on the tacts (1) that the naked eye appearances of the cultures on 
the ordinary media are alike ; (2) th.it microscopically they possess the following 
characters in common : — The specimens are very variable in size in single cultures ; 
the groups show marked polymorphism and many different shapes ; this poly- 
morphism is most marked in first cultures from the tumours or animal lesions, and 
in subcultures there is a species of reversion to a spherical organism which varies 
chiefly in the size ot the specimens ; mycelium-like growth develops in each case 
under certain circumstances. 
4. Macroscopic Appearance of the Cultures 
Type A 
Glucose agar. In twenty-four hours abundant white growth along the needle 
track on sloped media ; becomes heaped up along this track, and develops a yellowish 
and later a yellowish-brown colour. 
Glucose gelatine. Slow, but abundant, development of dense white growth 
along the needle track and on the surface of stab cultures. No gas formation in the 
medium. 
Potato. Yellowish-white abundant growth, develops as a broad heaped-up 
streak with crimped edges. 
