O- V. 



SECRETING STRUCTURES. 



Malpighi was the first to announce that all secreting glands are 

 essentially composed of tubes, with blind extremities.* Miiller, 

 by his laborious researches, has brought this department of the 

 anatomy of glands to its present comparatively perfect condition.f 

 Purkinje announced his hypothesis of the secreting function of 

 the nucleated epithelium of the gland ducts, but made no state- 

 ment to show that he had verified it by observation 4 Schwann 

 suggested that the epithelium of the mucous membranes might 

 be the secreting organ of these surfaces. Henle described mi- 

 nutely the epithelium cells which line the ducts of the principal 

 glands and follicles, but did not prove that these are the secreting 

 organs. The same anatomist has stated, that the terminal extre- 

 mities of certain gland ducts are closed vesicles, within w r hich the 

 secretion is formed, and which contain nucleated cells. Henle 

 has not, therefore, verified the hypothesis of Purkinje, although 

 he is correct in stating that the terminal vesicles of certain gland 

 ducts are closed.|| It will be shewn, that the secretion is not 

 formed, as Henle has asserted, in the closed vesicles, but in the 

 nucleated cells themselves. 



* Exewitatwnes de Structura Vicerum, 1665. 



t J. Miiller, De Gland. Struct. Penit. 1830. 



J Isis, 1838. 



Froriep. Notiz., 1838. 



|| Muller's " Archw." 1838, 1839. 



