SECRETION. 257 



Berzelius adopts the old division of secretions and excretions, 

 and makes the following remarks : 



" There are two classes of secreted fluids, viz. the secretions 

 properly so called, or the fluids intended to fulful sonje ulterior 

 purpose in the animal economy, and the excretions, which are 

 directly discharged from the body. The fluids of the former class 

 are all alkaline, and of the latter all acid. The excretions are 

 the urine, the perspired fluid, and the milk. All the other fluids 

 appear to belong to the former class. 



" The alkaline secreted fluids may be divided into two very 

 distinct species. The former of these contains the same quantity 



and a diminished proportion of carbon. It abounds in the young, so that those 

 parts, which at the beginning of life are almost entirely jelly, consist chiefly of 

 albumen as age advances : since it is not found in the fluids, it must be supplied 

 with its carbon again, and is, probably, reduced to the state of albumen. Dr. 

 Prout considers gelatine the most imperfect form of albuminous matter and the 

 counterpart of the saccharine principle of vegetables. 



Thejlbrinous are the muscular fibres, abounding in azote, and thus more com- 

 pletely animalised, resembling the fibrin of the blood, apparently their source. 



The oleaginous are the fat, marrow, and secretions of sebaceous glands, and 

 perhaps the milk, as its properties depend so considerably upon oily matter. 



The resinous are the bile, cerumen, and urea, very similar to the former, but 

 owing their specific characters to a kind of resin. Osmazome is referred to this 

 class ; but what M. Raspail thinks of it was mentioned under the head of blood. 



The saline are the acids, alkalies, and neutral and earthy salts of the various 

 solids and fluids ; generally more copious in the fluids than in the solids, absent 

 in the simple oleaginous secretions, and abundant in the compound ; and still 

 more so in the resinous secretions. Their quantity is greatest in the bones, which 

 are principally phosphate of lime ; but, with this exception, the urine possesses 

 the greatest proportion, as well as the most variety. 1 . In some secretions they 

 are absent ; as the fat. 2. In some they exist in definite quantity, and this dif- 

 ferent from that in the blood ; as the saliva. 3. In others, they are found in the 

 same quantity, and of the same nature, as in the blood ; such is the fluid of 

 serous membranes. 4. In some, they are different from the salts of the blood, 

 and of variable quantity ; as the urea. These four divisions are i. The solid 

 and albuminous, the gelatinous, and simple oleaginous, ii. The mucous, fibrinous, 

 compound oleaginous, iii. The liquid albuminous, iv. The aqueous and resinous. 



This arrangement is certainly good ; but, like every artificial arrangement of 

 natural objects, convenient for general views and memory, rather than correct. 

 For example, the semen is mucous, but unlike every other fluid : the gastric juice 

 and cerebral substance are equally sui generis. Fibrinous matter as well as mucus 

 exists in semen, and is probably, indeed, its specific part : albumen exists abund- 

 antly in milk, united into an emulsion with the oleaginous portion. The bile 

 and urine have few properties in common j and urea is certainly not a resinous 

 substance. 



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