OF THE GLANDS. .'321 



organized substance. The vessels carry to it the materials 

 contained in the blood, the production is even probably dis- 

 posed or prepared by the arrangement of the vessels and the 

 mode of circulation which results from it; but it is in the tis- 

 sue which forms the radicles of the excretory ducts that we 

 must seek for its essential and immediate instrument. Se- 

 cretion generally and glandular secretion in particular, are 

 evidently submitted to nervous influence; the effects of the 

 passions on secretions in general, those of diseases, of hyste- 

 ria, of hypochondria, &c. are sufficiently known. Brodie's 

 experiments have confirmed that which direct observation had 

 taught. 



The application of a ligature to the veins of a gland greatly 

 augments its secretion. 



489. The /first part which begins to be formed in the 

 glands is their excretory duct. In the embryo, this canal is 

 free and floating, as in insects. The glands are afterwards 

 lobate, for instance the kidneys, as they are in the arachnides 

 and crustacea. They are generally very voluminous in the 

 foetus and in the child. They diminish in proportion as the 

 organs of the animal functions are developed. Some change 

 their situation at the time of birth: these are the testicles and 

 ovaries. These glands and the mammae are greatly developed 

 at the epoch of puberty and wither in old age. 



490. The glands present many individual varieties and 

 vices of conformation. Some are sometimes entirely wanted: 

 those of generation are mostly subject to this circumstance. 

 One of the double glands may be wanting or be less volumin- 

 ous than the other. Some remain often lobate, or very vo- 

 luminous, as in the foetus. Others are sometimes united as 

 the two kidneys in one. Others may keep their primitive 

 situation, as the testicles and ovaries; these latter are some- 

 times, on the contrary, protruded out of the abdomen. The 

 kidneys also may be situated a great deal too low, or in the 

 pelvis. 



491. We often observe the atrophy of the glands, either 

 in consequence of external pressure, or of an accidental pro- 

 duction developed in their thickness: this also occurs for want 



