542 
morphology and virulence. In their work they give a history of in- 
vestigations similar to their own which strengthens the evidence for 
the conclusion that we can find nothing in the morphology and viru- 
lence of tubercle bacilli to encourage us to undervalue the importance 
of those from bovine sources for public health. 
Fibiger and Jensen.® who likewise obtained typical bovine bacilli, 
virulent for cattle, from human lesions, recall that the imperial Ger- 
man health office examined 39 cases of primary tuberculosis of the 
human intestines and mesenteric glands and found that 13 among 
them were caused by bacilli of the bovine type. Later investigations 
made by Fibiger and Jensen are summed up as follows: Though bo- 
vine types of tubercle bacilli are more commonly isolated from bovine 
lesions and human types from human lesions, there are cultures that 
must be considered as transition forms, as they have some of the 
characteristics of bovine and others of the human type. * 6 
Gorter,® after a careful study of tubercle bacilli from human and 
bovine lesions, found 7 among 21 cultures from human sputum which 
lie regards as identical with the transition forms between human and 
bovine bacilli which he says are described by Rabinowitsch. He con- 
cludes that human and bovine bacilli are not different varieties, and 
that the conversion of the one type into the other actually oceurs. 
Sargo and Suess a showed that mutations occur in human tubercle 
bacilli and other types, which speak against grouping tubercle bacilli 
from animals of different species as special varieties. 
Yon Behring, e who ranks as one of the most widely recognized 
authorities on tuberculosis, found cultures of tubercle bacilli isolated 
from man of low virulence for cattle, and others of higher virulence 
for them than many cultures of bovine origin. He declares himself 
as opposed to the view that bovine tubercle bacilli may be harmless 
for man. and calls attention to the fact that they generally have a 
higher grade of virulence than human bacilli, and are therefore to be 
regarded as more dangerous. 
The British royal commission on human and animal tuberculosis 1 
concluded from its investigations that cow's milk containing bovine 
tubercle bacilli is clearly a cause of tuberculosis, and of fatal tuber- 
culosis in man. and that a very large portion of tuberculosis con- 
tracted by ingestion is due to tubercle bacilli of bovine origin. 
a Berliner Klinisctie Wochenschrif t, Nos. 4 and 5, 1907. 
6 Presented at the joint session of Sections I and VII of the International 
Congress on Tuberculosis, Washington, D. C., 1908. 
c Zeitschrift fur Tuberkulose, Yol. XI, No. 8, 1907. Also Inter. Centralb. fur 
die ges. Tuber. Fors., Yol. II, No. 1, 1907. 
d Centralb. fur Bac-teriologie, etc., Yol. XLIII. Part I, pp. 422-529. 
e Berliner Tierarz. Wochens., Xo. 47, 1902. 
f Jour. Royal Institute of Public Health, Yol. XY. Xo. 3, 1907. 
