NOTES 475 



95 In the nautilus, this is preceded by a capacious crop. 



96 In the shark, this is impossible, owing to a great number of fringes in 

 the gullet hanging down toward the stomach. 



97 At the beginning of the large intestine in the lizards (and in many 

 vertebrates above them, especially the vegetarian orders), there is a blind 

 sac, called cacmn. 



98 The crocodile is said to swallow stones sometimes, like birds, to aid 

 the gastric mill. 



99 In the crop of the common fowl, vegetable food is detained sixteen 

 hours, or twice as long as animal food. The dormouse, among mammals, 

 has an approach to a crop. 



100 In invertebrates, the gizzard, when present, is situated between the 

 crop and the true stomach ; in birds, it comes after the stomach. 



101 The tapeworm has no digestive apparatus, but absorbs the already 

 digested food of its host. This is no exception to the rule. The chemical 

 preparation of the food has preceded its absorption. 



102 \y e fi nc [ t ne mos t abundant saliva in those mammals that feed on 

 herbs and grain, but its action on starch is extremely feeble. 



103 The acid in the gastric juice has an important function in killing or 

 preventing the growth of bacteria which are taken in with the food. The 

 gastric juice also dissolves the albuminous walls of fat cells, thus permitting 

 the contained fats to escape. The drops of fat fuse together into larger 

 masses, which are later broken up into droplets or emulsified by the pan- 

 creatic juice. 



104 It is probablq that the digestive part of the alimentary canal in all 

 animals manifests a similar mechanical movement. It is most remarkable 

 in the gizzard of a fowl, which corresponds to the pyloric end of the human 

 stomach. This muscular organ, supplying the want of a masticatory appa- 

 ratus in the head, is powerful enough to pulverize not only grain, but even 

 pieces of glass and metal. This is done by two hard muscles moving 

 obliquely upon each other, aided by gravel purposely swallowed by the 

 bird. The grinding may be heard by means of the stethoscope. 



105 Chyle is opaque in carnivores ; more or less transparent in all other 

 vertebrates, as in birds, since the food does not contain fatty matter. 



106 In fishes, the villi are few or wanting. In man, they number about 

 10,000 to the square inch. 



107 Except, perhaps, the tendons, ligaments, epidermis, etc. 



108 The blood is colorless also in the muscular part of fishes. That of 

 birds is of the deepest red. The coloring matter of the red blood in worms 

 is not in the corpuscles, but in the plasma. 



109 Coagulation may be artificially arrested for a brief time by common 

 salt. Arterial blood coagulates more rapidly than venous. The disposi- 

 tion of the red corpuscles in chains, or rouleaux, does not occur within the 

 blood vessels. The cause has not been discovered. 



