REVIEW — TROPICAL MEDICINE, ETC. 129 



(2) Physical examiuatiou of the udder and of its glands will greatly assist in arriving at a correct conclusiou, Milk — 



if the reaction to tuberculin is positive. continued 



(3) The microscopic examination of the deposits from milk after centrifugalising is not very satisfactory, 

 especially as acid-fast bacteria indistinguishable from the tubercle bacilli may be present. Injection of the 

 deposit into guinea-pigs with the object of inducing lesions is unsatisfactory, Ijecause of the length of time 

 that must elapse Ijofure the lesions become manifest. For this reason I have not included the use of laboratory 

 media for the isolation of the organisms, as the time occupied is too long and the results are too uncertain. 

 If, however, the suspected organisms are relatively abundant, the isolation of the acid-fast bacteria may be 

 attempted to ascertain if these develop within a few days ; if they do, then they are not tubercle bacilli ; if there 

 be no development the negative evidence may be taken as favouring the diagnosis of tubercle. 



(4) Harpooning the udder. Provided the owner of the animal is willing, there is no difficulty in carrying 

 out this simple operation. It goes without saying that an aseptic operation is desirable. The tissue removed 

 may be examined histologically for the tubercle bacilli and the characteristics of tuberculous lesions. The 

 presence of acid-fast bacilli in the tissues, even if the anatomical elements are not clearly indicative of 

 tuberculosis, is, in my opinion, sufficient for a positive diagnosis, inasmuch as the acid-fast bacilli of raiUc probably 

 gain access to the milk after it has left the cow. 



It must be noted, however, that Much^* has recently found in cattle forms of the 

 tubercle bacillus which are not acid-fast, distinguishing two types — a rod-shaped form 

 which is partly granular and a granular form consisting of granules lying singly or clustered 

 into irregular groups. These were found in the lungs of infected cattle, and nothing is 

 said about their presence in milk, but it is evident that such aberrant forms must now be 

 taken into consideration. 



Mammitis, due to the presence of streptococci, is discussed as is the finding of 

 streptococci derived from abscess in the gland or merely from the surface of the udder. 



They are not necessarily abundant unless the milk contains pus, and if it does, diagnosis is not difficult, 

 because the jjus cells are readily found in the precipitate following centrifugalisation. It would be well, in this 

 connection, to remember that numerous cells, leucocytes and epithelial cells may be present free in the perfectly 

 normal acini of the gland, and tliat these cells may be swept away by the secretion and appear in the milk. 

 There is not much difficulty, however, in recognising the pus cells as distinguished from the leucocytes, and the 

 number is always an admirable guide. Numerous cells will indicate pus or a catarrhal condition, few cells have 

 no pathological significance. 



This leads one to consider several papers on the significance of leucocytes and 

 streptococci in milk. 



Savage'^ believes that at— 



The present day (1906) we are not in a position to frame satisfactory bacteriological standards for milk, and 

 until more precise knowledge is acquired, it will not be possible for milk examination to take a place at all 

 comparable to that which the bacteriological examination of water oi:'cupies. The significance of streptococci in 

 milk, he says, is of great practical importance, and the presence of pus in milk is also of considerable importance. 

 That milk should not contain pus few will deny, but, he asks, what constitutes pus in milk ? All milk contains 

 leucocytes. When does a leucocyte become a pus cell, and what distinguishes the one from the other ? What 

 number of leucocytes, or pus cells, constitutes pus in milk ? 



He sets himself to answer these questions. 



The technique of the examination for streptococci and B. coli, and the method of 

 enumerating leucocytes, is given. The result showed a striking prevalence of streptococci. 

 In sixty-eight milk samples examined they were present in forty-five, or 66 per cent, 

 when 1 c.c. of the milk was examined. They can only come from the interior of the udder 

 or from unclean manipulation. This can be determined by the B. coli examination. The 

 precise value and significance of these streptococci is difficult to determine, but it is 

 noticeable that they more closely approximate to the streptococci most common in human 

 faeces (Houston) than to those more frequently found in saliva (Gordon). In particular 

 they agree with the former, in that they all, with one exception, were found to ferment 

 salicin, while the great majority of streptococci from saliva, isolated by Gordon, fail to 

 do so. Savage notes that if future work confirms this provisional deduction that all 

 streptococci from cows' milk ferment salicin, then the finding of streptococci with this 

 character in the throats of persons suffering from milk-carried streptococcal outbreaks may 

 become valuable evidence, as showing that these streptococci were of bovine origin and 

 causally connected with the outbreak. The work indicated that there was an absence of 

 any relationship between leucocytes and streptococci, while Savage states that he was 

 unable to differentiate between a leucocyte and a pus cell or to lay down an arbitrary 

 standard as to what number of leucocytes per cubic millimetre is to be designated pus 

 in the milk. 



» Much, H. (April 6th, 1908). Berl. Klin. JFoch. 



■ Savage, W. Q. (April, 1906), " Streptococci and Leucocytes in Milk." Journal of Hygiene, Vol. VI. 

 • Article not consulted in the original. 



