212 BACTERIA IN MILK AND MILK PRODUCTS 



suffering from diphtheria are foci of infection. The exact channels 

 of infection differ under varying circumstances ; but, in general, the 

 source of infection is the throat and mouth of the patient. Anything 

 which comes into contact with the mucous membrane becomes 

 infected. Thus handkerchiefs, sweets, children's toys, etc., may act 

 as the vehicles of contagion. The mucus and saliva may also be 

 infective, and in speaking, kissing, coughing, or expectorating such 

 mucus (probably rich in bacilli) may be disseminated in very fine 

 particles, and so carry the disease. It is by such means that the 

 disease is spread. Moreover, there is the fact of the long period 

 during which the human throat may remain infective. Professor 

 Sims Woodhead has recently stated that the persistence of the 

 diphtheria bacillus for periods up to eight weeks is of very common 

 occurrence. (3) Kichardiere and Tollemer * and others have proved 

 that the dust floating in the air of a diphtheria ward may contain 

 large numbers of diphtheria bacilli, and in this way milk and other 

 foods may become contaminated. 



Between 1878 and 1883, certain outbreaks of diphtheria due to 

 milk appeared to suggest that the cow itself might suffer from 

 diphtheria. The discovery of the Klebs-Loffler bacillus in 1883 

 furnished the basis for experimental work, and in 1886 Dr Klein 

 undertook some experiments to ascertain whether or not diphtheria 

 was inoculable into cows. He took for the experiment two healthy 

 milch cows which had calved some three or four weeks previously. 

 One c.c. of broth culture of B. diphtheria (derived from human 

 diphtheritic membrane) was injected under the skin into the sub- 

 cutaneous tissue of the left shoulder in each of the two cows. Two 

 or three days after the inoculation (a) the temperature rose (to 

 40'6), and the animals suffered from slight general malaise. On 

 the third day (b) a tumour appeared at the site of inoculation, which 

 steadily increased in size to the seventh day. On the fifth day (c) 

 a papular eruption appeared on the udder and hind teat. In addition 

 to the papules there were half a dozen vesicles, and some round 

 patches covered with brown crusts. The process of eruption was 

 mature by the eighth day. In the lymph of the vesicles and pustules 

 the B. diphtherias could be demonstrated, according to Klein, both 

 microscopically and by culture. He therefore concluded that the 

 B. diphtherice, as such, inoculated into the shoulder of the cow, was 

 received into the general system of the cow, and produced its effects 

 not in the viscera, but on the udder as a specific eruption, and that 

 before the end of five days after inoculation, was finally excreted in 

 the cow's milk. " The presence of the diphtheria bacillus," he wrote, 

 " could with certainty, by microscopic and culture observations, be 

 demonstrated in the rnilk of the cow collected under all precautions ; 

 * Gazette des Maladies Infantile*, 1899, No. 10. 



