368 A YEAR IN SCIENCE 



is not fully known. Some white corpuscles are pro- 

 duced in them. To some extent they also act as filters, 

 for the lymph, after passing through them, has had 

 most of the bacteria removed from it. These are prob- 

 ably destroyed in the lymph glands. 



Adrenal bodies. Just in front of each kidney there 

 is a small gland, called the adrenal body. The substance 

 which it secretes influences the muscles in the walls 

 of the arteries. As a result they contract and reduce 

 the size of the artery. The secretion from these bodies 

 helps to regulate the size of the blood vessels and 

 consequently to regulate the blood pressure. An extract, 

 adrenalin, is made from the adrenal bodies of sheep. 

 This is used to check hemorrhages. 



Thyroid glands. The thyroid glands are located on 

 the ventral side (front) of the neck just a little below 

 the larynx. The secretion from these glands seems 

 necessary for the proper nourishment and development 

 of the body. Without them both the body and mind 

 are not fully developed, a condition known as cretin- 

 ism. Sometimes the glands become enlarged and pro- 

 duce a goiter. In that case they produce too much 

 secretion and the activities of the cells become greatly 

 increased. A very rapid pulse, headaches, and some- 

 times insanity may result. Goiters should not be 

 neglected. As soon as any enlargement of these glands 

 appears a physician should be consulted. 



An extract is made from the thyroid glands of 

 sheep, which is used in cases w r here the thyroid glands 



