328 TRANSLATIONS. 



composition of the blood and that of the translation, as in the 

 dropsical effusions ; but we rather observe that the fluids stand in 

 an inverse relation to one another, the blood being poorer in water, 

 poorer in salts, and far richer in albumen, than the effused fluid. 

 (See our observations on the evacuations and the blood in cholera, 

 pp. 151 and 264.) 



The salts occurring in the transudations are precisely similar in 

 their nature to those of the intercellular fluid, and they are found 

 in almost exactly the same relative proportions to one another in 

 the transudation and in the blood-serum ; as in the latter fluid, the 

 chlorides considerably preponderate over the phosphates, sul- 

 phates, and carbonates, and the soda-compounds over those of 

 potash. A very important exception to this rule, in so far as 

 the physiology of secretion is concerned, has been observed by 

 C. Schmidt in the constitution of the salts which occur in the 

 fluid within the lateral ventricles of the brain (the transudation from 

 the choroid plexus). Whilst the transudation from the pia mater 

 and arachnoid contains the salts in precisely the same proportions 

 as occur in the fluids of other serous membranes, the mineral consti- 

 tuents here contain a great excess of potassium-compounds and 

 phosphates, so that the proportion of the potassium to the sodium, 

 and that of the phosphates to the chlorides, approximates more 

 nearly to that which is presented by the salts contained in the 

 blood-cells. While (according to Schmidt) there are contained in 

 the salts of the transudation from the peripheral cerebral capillaries 

 2*8 g- of potassium with 40'Q of sodium (a ratio almost identical with 

 that which is presented by the salts of the serum), the salts of 

 the transudation from the choroid plexus contain on an average 

 17'8-g- of potassium, and only 27'2-g- of sodium. In the same manner 

 the constitution of the transudation within the lateral ventricles 

 approximates to that of the blood-cells in regard to the chlorides 

 and phosphates ; while in 100 parts of the salts of the serum there 

 are contained 5*6 of phosphoric acid with 45*2 of chlorine, Schmidt 

 found 8*9^ of phosphoric acid and 37'6-g of chlorine in the salts in 

 central hydrocephalus. Hence the cerebro-spinal fluid is not to be 

 regarded as a mere transudation or filtrate from the blood, but as a 

 peculiar secretion in whose formation the blood-corpuscles appear 

 to take an essential part in so far as the salts are concerned. 



We may further readily convince ourselves that alkaline car- 

 bonates are also present in the normal alkaline transudations, by 

 placing fresh fluids of this kind which have been obtained by para- 

 centesis in a vacuum, and as completely as possible removing the 



