138 MILK [vm 



gard to this, there is little precise information. It is, 

 as all are aware, a preparation usually made from the 

 stomach (the rennet stomach) of the calf; but it is 

 also found in the stomach of the sheep, and, although 

 in smaller quantity, in the stomachs of many other 

 animals, the deer and the chamois, as well as in 

 fishes and birds. Whether it is always of identi- 

 cally the same composition when obtained from these 

 different sources or not, it is impossible to say. So 

 much, at any rate, may be said, that it is possible 

 to gain from the stomachs of the above-mentioned 

 animals, on treating them with salt or lactic acid, a 

 substance which exerts an action on milk similar to 

 that exerted by rennet from the calf's stomach. 

 Eennet has also been found in the human stomach. 

 It is a secretion of certain glands embedded in the 

 lining of the stomach, and is most abundant in the 

 very young animal, especially . during the period of 

 suckling. As the young animal, however, gradually 

 ceases to depend for its food on milk, the production 

 of rennet decreases. It has also been found in a 

 number of plants. For example, the juices of the 

 fig tree, the artichoke, certain kinds of thistle, and 

 the melon tree, as well as other plants, have been 

 found to contain a substance, the action of which is 

 similar to that of rennet. Whether, however, this 

 substance is identical in all cases, and whether it is 

 the same as the rennet obtained from the calf's 



