SECRETION. 417 



stricter, and thus arrests hemorrhage. On striated muscle it pro- 

 longs contracture and thus causes the muscle to be slower in relaxing. 



Nearly all the adrenalin is destroyed in the body, but I have 

 shown that a minute quantity is excreted by the kidneys. One one- 

 millionth of a gram of the dried gland will elevate the arterial 

 tension. 



The splanchnics are supposed to contain the secretory nerves of 

 the adrenals. 



In rabbits during pregnancy the suprarenal bodies enlarge, the 

 outer cortex being twice the size of the medulla and inner cortex. 

 Sexually precocious children have hypertrophied suprarenal capsules. 

 Atrophy of suprarenal capsules is associated with want of pubic hair 

 and of development of the genital organs. Hence the cortex of the 

 adrenal is probably connected with the growth of the body and the 

 development of puberty and sexual life. Eepeated injection of 

 adrenalin produces an experimental arteriosclerosis, with calcium 

 deposits in the middle coat of the artery. Toxic doses produce agita- 

 tion, dyspnoea, convulsions and death with pulmonary oedema and 

 sometimes fibrillafy twitchings of the ventricular muscles. 



THE THYMUS. 



The thymus body is a temporary organ which increases in size 

 from the embryo up to two years after birth, and subsequently 

 dwindles away. It occupies the upper part of the anterior medias- 

 tinal cavity behind the sternum and extends into the neck frequently 

 to the thyroid gland. It rests upon the pericardium, aorta, and the 

 trachea. It is a flat, triangular body, consisting of a pair of lateral and 

 unequal lobes. It is of a pinkish-cream color, and varies in size and 

 weight not only according to age, but also in different persons. At 

 birth it is about two inches long and one and one-half inches wide at 

 the lower part and two or three lines thick. It is composed of numer- 

 ous angular lobules mixed with connective tissue. The lobules are sub- 

 divided into follicles, and each follicle has a cortex and medulla. In 

 the medulla are spherelike bodies known as the concentric corpuscles 

 of Hassall. 



Chemical Composition. The thymus is principally a lymph- 

 gland. Nothing special is known of the concentric corpuscles. The 

 presence of extractives, like xanthin, hypoxanthin, leucin, and adenin 

 has been noted. The alkaline reaction of life becomes rapidly acid 

 after death. The acid is sarcolactic acid. 



The main constituent of the cells is proteid, especially nucleo- 



27 



