The Living Machine 321 



condition of under development both mental and physical, 

 which is known as cretinism from tlie French word cretin. 

 Feeding the extract of the thyroid gland of a sheep, or the 

 gland itself, either raw or cooked, results in great increase in 

 growth and development of both mind and body in such cases. 

 The use of adrenalin (extract of the adrenal ghmd of some 

 animal) is a common practise in certain diseases and in- 

 juries as, for example, asthma, in which injections of the 

 drug relax the bronchial muscles, and greatly relieve the suf- 

 ferer. Attached to the lower, central part of the brain is a 

 small gland, the pituitary body, which some enthusiastic the- 

 orists have fancied to be the seat of the soul. If this gland 

 be partly removed from a young puppy it ceases to grow ex- 

 cept for the accumulation of fat. It keeps its puppy hair 

 and milk teeth, while the development of the genital organs, 

 and of the intelligence is much retarded. 



After partial digestion in the stomach, the food is further 

 digested in the upper end of the small intestine. The di- 

 gestive juices come in part from the liver and wall of the 

 intestine itself, and in part from the pancreas. When the* 

 partly digested and acid food passes from the stomach into 

 the intestine, it causes the pancreatic juice to flow as auto- 

 matically as the movement of the piston in a gasoline engine 

 causes the intake of gasoline from the supply tank. The 

 pancreas is activated by the acid food in the intestine. It 

 was formerly supposed that this activation was effected by 

 reflex nerve action, but we now know of an entirely differ- 

 ent mechanism for this function. If an acid extract of the 

 lining of the intestine be injected into the blood it causes the 

 pancreas to secrete its juice as surely as does the presence 

 of acid food in the intestine ; while similar extracts of other 

 organs have no such effect. Here there is clear evidence of 

 an internal secretion formed by the intestine, which reach- 

 ing the pancreas via the blood causes the latter to act. A 

 beautiful example of the chemical control of bodily func- 

 tions. 



On the run of any through train between the terminals 

 of a great trunk line there is a change of engines about once 

 every 200 or 250 miles. Neither engine nor crew can give 

 as effective service if operating for greater distances. The 

 non-living, as well as the living machine needs rest after a 

 certain period of work. 



Recently the well-known surgeon, Crile of Cleveland, has 

 advanced an interesting theory which he calls the "kinetic 

 drive" to explain the running down of the human mechan- 

 ism. In the "kinetic drive" of modern life, when the hu- 

 man machine is being driven at top speed, stored or poten- 



