6 E. KLEIN. 
fibres is very marked, and occurs in a large number of places. 
It was described and illustrated in the ‘Report of the Medical 
Officer of the Local Government Board, 1889-90,’ pp. 173 and 
174, plates xiv, xv, and xvi; and I have to add here that 
sections of the tumour stained in a mixture of eosin and 
methyl blue show this in beautiful contrast, the growing threads 
blue, the muscular substance red; and it seems to me that one has 
only to examine such a specimen to at once see that the threads 
are actively growing; of an involution there can be no question. 
Dr. Abbott, in the ‘ Journal of Pathology and Bacteriology,’ 
vol. ii, while agreeing that the thread-like bacilli with terminal 
swellings are not involution forms, and are present in the 
growing artificial cultures (on serum), does not agree to their 
being comparable to the growing ends of hyphe. This dif- 
ference seems, however, merely a question of words; all that 1 
maintained was that the threads with knobbed ends strongly 
resemble growing ends of hyphe, and that such a change in 
bacilli as I described in artificial cultures, and particularly in 
the growing threads in the cow’s tumour, if it is not due to 
involution, as it certainly is not, is only explained by its 
representing a relationship to a mycelial fungus, perhaps the 
Saccharomyces mycoderma or an Oidium form. 
(d) From the milk of cows successfully inoculated with 
cultures of the diphtheria bacilli (Report, 1889-90 and 
1890-91) I have isolated by culture the diphtheria bacillus, 
and in the gelatine cultures they showed this change in a con- 
spicuous manner ; the colonies in their young state are almost 
entirely made up of thread-like forms with terminal knob-like 
and club-shaped swellings (figs. 5 and 6) quite unlike the typical 
bacilli. Here the bacilli are actively growing, and therefore 
it is quite out of place to regard these forms as due to involu- 
tion; and if they are not involutions, their similarity in 
growth and shape strongly suggests the view that I have put 
forward, viz. that they are comparable to the hyphe of a 
mycelial fungus, e.g. Saccharomyces mycoderma. In these 
threads with local accumulations of their substance, and with 
terminal knob-like or club-shaped enlargement of their proto- 
