GENERAL STRUCTURE OF THE BODY. 35 



its life for the health of the part. Thus a wound in the 

 foot, if infected, may cause irritation and enlargement 

 of the glands at the knee and in the groin. 



The lymphatic glands are frequently the seat of tu- 

 bercular infection, especially in the neck, and are en- 

 larged in scarlet fever, tonsillitis, and diphtheria. In 

 syphilis there is general glandular enlargement, and the 

 glands in the groin become enlarged in all diseases of 

 the genital organs. In malignant growths, such as can- 

 cer, the extension of the disease is often along the lines 

 of the lymphatics. 



Glands. Of glands in general a word might now be 

 spoken. They are of two kinds, excreting and secret- 

 ing, and, when simple, are formed by the folding in of 

 a free surface, as in the case of the salivary, gastric, and 

 sebaceous glands, the cells at the gland becoming so 

 modified as to be able to perform the function of excret- 

 ing or secreting. In racemose glands the gland is 

 broken up into many pockets. Excreting glands take 

 from an organ or from a part substances which have out- 

 lived their usefulness and are to be cast out of the body, 

 while the secreting glands form from the blood sub- 

 stances that did not exist in it before, but which are of 

 use to the body, as the ptyalin of the saliva. A strict 

 line cannot, however, be drawn between the two kinds 

 of glands, most glands partaking more or less of both 

 functions, though the sebaceous and sweat glands are 

 probably purely excreting glands and the salivary glands 

 are almost purely secreting. The glands, moreover, 

 are more or less interchangeable in their functions, that 

 is, they have vicarious function, and one gland can take 

 up and do for another what that other is for some reason 

 unable to do. In jaundice, where there is stoppage of 

 the bile duct, the kidneys help out the liver by excret- 

 ing the bile. If one kidney is removed the other does 

 work for both, and the glands of the skin may help out 

 the kidneys or vice versa. Hemorrhage from the lungs 

 sometimes occurs in suppression of the menses. 



