GUM. 273 



borax, or with sulphate of iron (Lassaigne).* The animal was 

 killed at the end of three days, four hours after it had taken the 

 last dose of gum (10 grammes at a time), but no trace of gum could 

 be discovered by means of these reagents, either in the very small 

 quantity of chyle that was collected from the thoracic duct, or in 

 the blood after the coagulation of all the coagulable matters and the 

 exhibition of the aqueous extract. We cannot doubt, therefore, 

 that even if this substance admitted of resorption, it must only 

 pass in extremely small quantities, and very slowly, into the mass 

 of the juices; nor can we assume the probability of its rapid con- 

 version in the blood, since all chemical experiments prove that 

 gum is far less easily decomposed than other carbo-hydrates, as, 

 for instance, sugar, which, notwithstanding its ready decomposition, 

 may yet be detected in the blood. 



If we are not disposed to believe that the absorbing organs 

 possess the property of resisting the absorption of this extremely 

 soluble substance, the question arises, whether the facts hitherto 

 ascertained from physical experiments on the diffusion or trans- 

 udation of gum, afford any explanation of the above-named 

 physiological experiments. According to Graham, the diffusibility 

 of gum is only half that of starch-sugar, and four or five times 

 less than that of chloride of sodium, whilst, on the other hand, it 

 is more than four times greater than that of albumen. Jolly 

 found that the endosmotic equivalent of gum was considerably 

 higher than that of sugar. The simplest endosmotic experiments 

 with gum are, however, sufficient to show that animal mem- 

 branes are not impermeable to that substance. Physical experi- 

 ments only prove, therefore, that gum penetrates through animal 

 membranes less readily than many other substances 5 and it only 

 remains to show by further experiments what are the mechanical 

 conditions which cause so small a portion of gum to pass from the 

 intestinal canal into the blood ; for the experiments which I have 

 already mentioned do not by any means lead us to the conclusion 

 that positively no gum is absorbed, for silicate of potash, borax, 

 and sulphate of iron are such slightly sensitive reagents, that when 

 applied to a mixture of organic bodies (such as we have here to 

 deal with), they may fail in detecting very considerable quantities 

 of gum. It has also been asserted that turmeric is not 

 resorbed in the intestine ; but in my experiments I have detected 

 small quantities of it in the blood of rabbits, which had been made 

 to take daily a concentrated solution of this pigment. It must 



* Journ. de Chim. m^d. 3 S^r. T. 7, pp. 580-582. 

 VOL. III. T 



