150 



EXCRETION. 



hurtful. The menstrual discharge may be 

 regarded as strictly an excretion, though one 

 which is required only in the human species 

 and for a limited time. 



Berzelius stated several distinctions, which 

 he thought important, between the excVemen- 

 titious and recrementitious secretions in the 

 animal body, particularly that the former are 

 always acid, that each of them contains more 

 than one animal matter, and that their salts are 

 more numerous and varied than those in the 

 blood, while the latter have an excess of alkali 

 from the same saline ingredients as the serum 

 of the blood, and each contains only a single 

 animal principle, substituted for the albumen 

 of the serum. But these distinctions are cer- 

 tainly inapplicable in several instances, and the 

 only one of them which appears to be a general 

 fact, is the more complex saline impregnation 

 of the excreted fluids. 



III. It is unnecessary to dwell on the well- 

 known injurious effects, on the animal ceconomy, 

 of the suppression of any of these excretions. 

 It may, indeed, reasonably be doubted, whether 

 the rapidly fatal effects of obstructing the ex- 

 posure of the blood to the air at the lungs are 

 owing to the retention of carbon, or carbonic 

 acid ; it seems much more probable that the 

 cause which stops the circulation at the lungs 

 in asphyxia, is the suspension of the absorption 

 of free oxygen into the blood, rather than the 

 suspension of the evolution of carbon or car- 

 bonic acid. But even if the circulation could 

 be maintained, after the exposure of the blood to 

 the air is suspended, we know that the carbonic 

 acid which we have good reason to believe 

 would soon be in excess in the blood, would 

 then act as a narcotic poison. Of the effects of 

 suspension of the excretion by the skin we can- 

 not speak with certainty, because that is a case 

 which probably hardly ever occurs ; and if it 

 were to occur, the lungs and kidneys would 

 probably act as perfect succedanea. But it is 

 worthy of notice that at a time when the skin is 

 known to be nearly unfit for its usual functions 

 during the desquamation that succeeds exan- 

 thematous diseases, and especially scarlatina, 

 the lungs and the kidneys, on which an unusual 

 burden may thereby be supposed to be thrown, 

 are remarkably prone to disease. The effect of 

 suppression of the excretion of urine (i. e. of 

 ischuria renalis), whether occurring as a disease 

 in man, or produced by extirpation of the kid- 

 neys in animals, is uniformly more or less of 

 febrile symptoms quickly followed by coma 

 and death ; and in these circumstances it is 

 now known, that the urea may be detected in 

 the blood. A variety of morbid affections, and 

 particularly an affection of the nervous system 

 marked by inaptitude for muscular or mental 

 exertion, always follows the obstruction of the 

 excretion of bile, and absorption of bile into 

 the blood constituting jaundice. 



There are a few cases of intense jaundice 

 which terminate in coma and death as rapidly 

 as the ischuria renalis does, and with as little 

 morbid appearance in the brain to explain this 

 kind of fatal termination ; and in several such 



cases the remarkable phenomenon has been 

 observed after death, that the bile-ducts have 

 been pervious and empty* It is obvious, that 

 it is this last circumstance only, that can 

 make a case of jaundice analogous to cases 

 of the ischuria renalis. If it shall appear 

 to be a general fact, that the cases of jaundice 

 presenting this remarkable appearance on 

 dissection are those which terminate with 

 unusual rapidity in the way of coma, the 

 analogy will appear to be complete ; and when 

 such cases are compared with those, much 

 more frequently occurring, where the excretion 

 of bile is only obstructed, not suppressed, and 

 where months frequently elapse without any 

 bad symptom occurring, it appears a reason- 

 able conjecture, that the retention in the blood 

 of matters destined for excretion, is more 

 rapidly and certainly injurious than the re- 

 absorption of matters "which have been excreted 

 from the blood at their ordinary outlet, but not 

 expelled from the body. 



Although there is still much obscurity in 

 regard to the intention of the menstrual dis- 

 charge, yet it may be stated as a general fact, 

 that the suppression of this evacuation is more 

 frequently followed byinjurious effects (particu- 

 larly affections of the nervous system, or vica- 

 rious haemorrhage) than the stopping of an equal 

 amount of haemorrhage, going on equally 

 slowly, would be ; so that the general principle 

 applicable to other excretions is exemplified 

 here likewise. 



IV. The next question in regard to the ex- 

 cretions is, in what manner they are effected ; 

 and on this question, although we must profess 

 ignorance in the last result, yet it is instructive 

 to observe, what seems now to be well ascer- 

 tained, that the large size, and apparently com- 

 plex structure, of several of the organs of excre- 

 tion, appear to be no part of the contrivance 

 for the formation of these fluids from the blood. 



It is stated by Cuvier, as the result of a 

 general review of the structure of glandular 

 organs in different classes of animals, that pro- 

 ducts very nearly resembling each other, and 

 evidently answering the same ends, are formed 

 in organs where the structure, and the disposi- 

 tion of vessels are very various ; and again, 

 that substances the most widely different are 

 formed in organs that are in these respects ex- 

 tremely similar ;f and that this should be the case 

 will not appear surprising when we consider 

 the result of the most minute and accurate 

 observations on the ultimate structure even of 

 those secreting organs, which form substances 

 the most dissimilar to the general nourishing 

 fluid, either of animals or vegetables. " Chaque 

 cellule de la structure vegetale," says De 

 Candolle, " peut etre consideree comme une 

 vesicule organique et vivante, qui est entouree, 

 ou de cavites dans lesquelles abordent des 

 liquides, ou de cellules remplies elles-memes de 



* See Marsh in Dublin Hospital Reports, vol. iii. 

 Two cases of exactly the same description have oc- 

 curred within these few years in the Edinburgh 

 Clinical wards. 



t Lc9ons d'Anat. Comp. t. v. p. 214. 



