MILK 109 



local inflammatory or suppurative conditions. For these con- 

 ditions the number of cells present may be very high and in 

 cases of definite mastitis numbers as high as 300,000 per cubic mm. 

 have been found by the writer. 



This estimation may be very useful to detect the commencing 

 stages of mastitis and it may be said that in general when 

 cellular elements are present in numbers more than 800 or so 

 per cubic mm. they indicate the need for careful inquiry as to 

 the local conditions of the cow's udder or teats. 



For ordinary mixed milk samples this determination is of no 

 particular value. 



The significance of streptococci in milk is a complex and 

 difficult subject. They are undoubtedly very prevalent not only 

 in ordinary samples of market milk but also in samples of mixed 

 milk collected immediately after milking when no multiplication 

 in the milk can have taken place. For example the writer found 

 streptococci present in every sample of mixed milk (although 

 many were collected at the farm) in a large series which he 

 examined, when I c.c. was sampled and in over 80 per cent, 

 when O'l c.c. was examined. Also streptococci were present in 

 over half the samples of milk examined drawn direct from 

 the teats of cows. 



It would appear that there are four main sources of strepto- 

 cocci in milk, i.e. the teat passages and milk cisterns of healthy 

 cows, manurial contamination (streptococci are present in cow 

 manure O'l to 10 millions or more per gramme), stale milk from 

 unclean milk vessels and local disease of the cow (mastitis, etc.). 



It is obvious from these varied sources of origin that the 

 presence of streptococci in moderate numbers in milk samples 

 cannot be accepted as of necessity of prejudicial significance or 

 as pointing, without further investigation, to local disease in one 

 of the cows supplying the milk. 



Whether their presence in very large numbers in fresh milk 

 can be taken to indicate inflammatory disease of the milk- 

 secreting organs of one or more of the cows supplying is a 

 question which cannot be said to be at present settled, but it is 

 certainly an unsatisfactory condition and should lead to careful 

 examination of the cows. 



