\Preliminary remarJcs on immunity in animal kingdom 63 



allow the animal to see sand in the distance — the glands at once 

 begin to secrete fluid saliva. Tempt the dog with flesh — and 

 immediately a thick saliva appears ; show him dry bread — saliva is 

 secreted in abundance, even if the dog has no great desire to eat. 



The same phenomena may be observed in the stomach. Mechanical 

 stimulation by inert bodies, such as stones, provokes no secretion ; 

 but the suggestion of a meal or the sight of food is sufficient to call 

 forth a large quantity of gastric juice. The quantity and quality of 

 the gastric juice are regulated by the quantity and quality of the food. 

 Bread given to a dog provokes the secretion of a gastric juice endowed 

 with the greatest digestive power. That which flows after the ingestion 

 of milk contains only one- fourth as much pepsin. 



In spite of these differences in the gastric secretion in relation 

 to food, Pawloff" and his pupils have never been able to assure 

 themselves that there was any prolonged and chronic adaptation of 

 the gastric function. They were struck by the uniformity of the 

 digestive power of a great number of their dogs. Samoiloff* had 

 under observation three dogs placed on different diets. In spite of 

 the very long periods during which these diets were given, the gastric 

 juice, in all the dogs, presented the same j)roperties and manifested 

 no appreciable difference. This result harmonises with that indicated 

 above as obtained in the Actinians fed with blood by Mesnil. In spite 

 of repeated feedings on blood from the same species of animal, the 

 extract from the mesenterial filaments was in no way different from [68] 

 that of the fasting Actinians used for control. 



The pancreatic secretion is, in many respects, a more perfect type. 

 We have here to do with the principal agent in the digestive function, 

 without which the organism could not continue to exist. The advances 

 made in surgery have enabled us to remove the stomach, first in the 

 dog and then in man, and there are already several persons '^ from 

 whom the stomach has been removed and who, in spite of this 

 operation, have continued to live. A portion of the small intestine 

 may also be removed, but, in order that life may not be endangered, 

 a considerable portion of it must be left intact. It is evident then 

 that the pancreatic digestion is an admirably organised function both 

 in animals and in man. One of the main regulators of this process of 

 digestion consists in the great sensitiveness of the intestinal mucous 

 membrane. Just as the organs of the buccal cavity possess in the 



1 Arch. d. sc. Uol, St.-Petersb., 1893, t. ii, p. 698. 



2 Cf. Bull. Acad, de med., Paris, 1901, p. 17. 



