Sect. XXXVII. 3. 1. SECRETION, Sec. 36; 



chemical procefs, termed digedion ; which, however, chemiftry 

 has not yet learnt to imitate out of the bodies of living animals 

 or vegetables. This procefs feems very fimilar to the facchanne 

 procefs in the lobes of farinaceous feeds, as of barley, when it 

 begins to germinate ; except that, along with the fugar, oil and 

 mucilage are alfo produced •, which form the chyle ot ani- 

 mals, which is very fimilar to their milk. 



The reafon, I imagine, why this chyle-making, or facchanne 

 procefs, has not yet been imitated by chemical operations, is 

 owing to the materials being in fuch a fituation in reipecr. to 

 warmth, moifture, and motion } that they will immediately 

 change into the vinous or acetous fermentation ; except the 

 new fugar be abforbed by the numerous lacteal or lymphatic 

 veflels, as foon as it is produced ; which is not eafy to imitate 

 in the laboratory* 



Thefe lacteal vefTels have mouths, which are irritated into ac- 

 tion by the ftimulus of the fluid which furrounds them ; and by 

 animal felection, or appetency, they abforb fuch part of the ilu- 

 id as is agreeable to their palate $ thofe parts, for initance, 

 which are already converted into chyle, before they have time 

 to undergo another change by a vinous or acetous fermentation. 

 This animal abforption of fluid is aimed vifibie to the naked eye 

 in the action of the puncTa lachrymalia ; which imbibe the tears 

 from the eye, and di (charge them again into the noilriis. 



III. The arteries conltitute another refervoir of a changeful 

 fluid j from which, after its recent oxygenation in the lungs, a 

 further animal felection of various fluids is abforbed by the nu- 

 ■^merous glands ; thefe felect their refpective fluids from the 

 blood, which is perpetually undergoing a chemical change ; but 

 the felection by thefe glands, like that of the lacteais, which 

 open their mouths into the digetting aliment in the ftomuch, is 

 from animal appetency, not from chemical affinity ; fecretion 

 cannot therefore be imitated in the laboratory, as it confifts in a 

 felection of part of a fluid during the chemical change of that 

 fluid. 



The mouths of the lacteais, and lymphatics, and the ultimate 

 terminations of the glands, are finer than can eafily be conceived ; 

 yet it is probable, that the pores, or interfiUces of the parts, or 

 coats, which conftitute thefe ultimate vehcis, may ftill have 

 greater tenuity ; and that thefe pores from the above anai)-.- 

 muft poiTefs a fimilar power of irritability, and abforb by their 

 living energy the particles of fluid adapted to their purposes, 

 whether to rephice the parts abraded or difTolved, or to ejongatd 

 and enlarge themfelves. Not only every kind of gland is ihus 

 endued with its peculiar appetency, and felecU the material 



Vol. I. Y y agreeable 



