130 RRVIEW — TROPIOAL MEDICINE, ETC. 



Milk— As regards the presence of B. cnU, Savage considers this organism as always derived 



continued from outside the udder and a definite indicator of contamination during milk collection or 

 storage. 



Harris' has reviewed the whole subject, quoting numerous authorities and concluding 

 that : — 



(a) The statements of Kruse, HoUing, and Heinemann cast considerable doubt upon the value heretofore 

 entertained regarding the significance of streptococci in milk. 



(i) It is not excluded by the evidence that pathogenic streptococci are to lie found at times in milk ; in 

 fact, recorded observations make this certain, the contamination arising from clinically recognisable cases of 

 mastitis in the herds. 



(c) We arc not as yet in possession of any reliable method for distinguishing a non-pathogenic from a 

 pathogenic streptococcus. 



(rf) The sanitary significance of the so-called " pus cell " has been greatly overrated. More scientific attention 

 should be given to "the study of the phenomena of lactic leuoocytosis, together with a more accurate method of 

 enumeration, such as that of Doane and Buckley or of Savage. 



(c) Particularly, should more attention be given to veterinary inspection of the cows' udders, with less 

 absolute dependence upon laboratory examination of milk, for signs of infectious processes. 



A still more recent paper is that by Pennington and Eoberts,^ who, dealing with 

 Savage's statement as to leucocyte and pus cell, state : — 



However, it does seem possible, in a large percentage of cases, to determine, by considering the rel.ative 

 number of the various kinds of leucocytes going to make up the cell content of tlie milk, whether they are 

 polymorphonuclear, large or small mononuclear, eosiuophiles, etc. ; and by their- staining and appearance, whether 

 tliey are degenerated or in good condition morphologically, loose lying cells or collected into masses with 

 evidences of fibrin ; and from such observations it seems possible to determine whether the condition which 

 produces them is likely to be pathological or normal ; and finally summarise the results of their enquiries in 

 Philadelphia as follows : — 



A correlation of the finding of streptococci or of many leucocytes in milk by the laboratory, with the 

 physical condition of the cows in a herd maintained for the production of a very clean milk, would seem to 

 show that in many oases there is a connection between such findings and the condition of the cow, both in 

 relation to specific udder and to systemic affections. Such pai'allelism seems to obtain for the end of the 

 lactation period, for the beginning of an udder inflammation, for an attack of cow-pox, and, possibly, for 

 chemotactic conditions due to high feeding of animals constitutionally unable to transform the increased feed into 

 increased milk. 



The frequent laboratory examination of the railk of individual cows has materially assisted the herdsman in 

 preserving the good health of the animals and has stimulated more frequent and careful clinical observ.ations. 



It is believed, too, that such examinations are a very material factor in maintaining a bacterial count, 

 which, for the past thirteen months, averages 3267 organisms per c.c. when the milk is fi-ora twenty-six to forty 

 hours old. 



An interesting paper is that by Eobertson" on the milk supply of Edinburgh. He gives 

 Houston's standard for specific organisms in milk. 



(1) 1 c.c. should not give evidence of Bacillus cnteriiidis sporogeiics. 



(2) O'OOl c.c. should not give evidence of Bacillus coli communis. 

 (.3) O'OOl c.c. should not give evidence of streptococci. 



Primary sediment should not exceed, after twenty-four hours, 100 parts per 1,000,000 c.c. 

 Secondary sediment (after ccntrifugalisation) should not exceed 50 parts per 1,000,000 c.c. 



In obtaining a pure milk we should strive to limit the number of micro-organisms 

 to 20,000 per c.c, and if the Jiiilk is strained and refrigerated immediately after it is 

 drawn and tlie fore-milk thrown away, there should not be great difficulty in attaining 

 this perfection. He further states : — 



If there are a great number of micro-organisms in the milk, it proves that the 

 temperature of the milk has been kept too high, which is a condition favourable to the rapid 

 development of germs in such a good breeding medium ; and further, that the milk has been 

 produced under insanitary and uncleanly conditions. 



The special micro-organisms, B. coli communis and B. entcrilidis sporogencs, afford 

 direct evidence of the contamination of the milk with cow-dung or human exci'ement, 

 and cause diarrhoea, and are therefore of special importance in the consideration of infantile 

 mortality. 



> Harris, N. MoL. (May, 1904), "The Relative Importance of Streptococci and Leucocytes in Milk." Journal 

 of Infectious Diseases. Suppl. 3. 



' Pennington, M. E., and Roberts, E. L. (January 30th, 1908), "The Significance of Leucocytes and 

 Streptococci in the Production of a High Grade Milk." Journal of Infectious Diseases, Vol. V. 



^ Robertson, R. (October, 1907), "The Milk Supply of Edinburgh, with Suggestions for the Improvement 

 of Milk Supplies Generally." Journal of the Royal Institute of Public Health, Vol. XV. 



