376 MILK AND THE PUBLIC HEALTH CHAP. 



The subject has been submitted to direct experiment. A 

 considerable number of animal experiments have been carried 

 out, but since deductions from them to human feeding cannot be 

 accepted as altogether reliable, too much stress cannot be laid 

 upon them. On the whole they show no evident differences 

 as regards digestibility and nutritive value between raw and 

 cooked milk. As illustrating the kind of investigations made 

 the following may be mentioned. 



Briining : used litters of newly-born animals, feeding part 

 with raw and part with boiled milk. When the milk of 

 another species was used better results were obtained with 

 boiled than with raw milk, but when the animals were fed on 

 raw milk of their own species they did better than those 

 receiving it cooked. He experimented with pigs, dogs, rabbits, 

 guinea-pigs, and goats. 



Lane-Claypole 2 experimented with young rats, starting 

 her experiments with these animals when they were, as nearly 

 as possible, a fortnight old. Her careful investigations showed 

 no diminution in nutritive properties for rats when the milk 

 was boiled, or even when evaporated and dried at 120 C. 



Some experiments have also been carried out on compara- 

 tive lines with children. Koplik, for example, fed infants 

 with raw and cooked milk, estimating the nitrogen in the 

 faeces. He apparently did not also estimate the nitrogen in 

 the urine. On the whole his experiments showed that the 

 percentage amount of nitrogen unabsorbed was practically the 

 same whether the milk was pasteurised or sterilised, but that 

 the percentage unabsorbed was rather less with raw milk. 

 Finkelstein 3 carried out experiments with healthy infants, on 

 sick children, and on small ill-developed children. He found 

 no superiority for either raw or cooked milk, since neither the 

 progress of the healthy children nor the recovery of the sick 

 were apparently influenced by the kind of milk. 



From the clinical point of view, results being based upon 

 the general development of the infants and not upon exact 

 chemical data, very diverse opinions have been expressed. On 

 the whole, it would appear, taking all the facts into considera- 



1 Zeit.fur Tiermed., 1906, pp. 198, 277. 



2 Journ. of Hygiene, 1909, ix. p. 233. 



3 Therap. Monats., October 1907, p. 508. 



