CLASSIFICATION OF GLANDS. 35 



the mucous membrane ; while the ordinary racemose glands 

 are nothing more than collections of follicles around the ex- 

 tremities of excretory ducts. These ideas concerning the 

 general anatomy of the glands date from the observations 

 of Malpighi, 1 who was the first to correct the old notion 

 that the secretions were discharged into the glandular organs 

 through openings in the blood-vessels. It is evident that 

 nothing could have been known of the mechanism of Secre- 

 tion before the connection between the arteries and veins 

 had been ascertained, which, it will be remembered, was also 

 discovered by Malpighi. Although the ideas of Malpighi 

 were not at first generally received, more recent observations 

 with the microscope have shown that they were in the main 

 correct ; though, from the imperfection of his optical instru- 

 ments, Malpighi was unable to investigate the minute struc- 

 ture of the glands very thoroughly. 



Anatomical Classification of Glandular Organs. The 

 organs which produce the different secretions are susceptible 

 of a classification according to their anatomical peculiarities, 

 which greatly facilitates their study. They may be divided 

 as follows : 



1. Secreting membranes. Examples of these are the se- 

 rous and synovial membranes. 



2. Follicular glands. Examples of these are the simple 

 mucous follicles, the follicles of the stomach, the follicles of 

 Lieberkiihn, and the uterine follicles. 



3. Tubular glands. Examples of these are the cerumi- 

 nous glands, the sudoriparous glands, and the kidneys. 



4. Racemose glands, simple and compound. Examples 

 of the simple racemose glands are the sebaceous and Meibo- 

 mian glands, the tracheal glands, and the glands of Brunn. 

 Examples of the compound racemose glands are the salivary 



1 MALPIGHI, Exercitationes A natomicce de Structura Vlscerum. Opera Omnia, 

 Ludg. Batav., 1687, tomus ii., p. 257. 



