1864.] On the Amyloid Substance in the Animal Economy. 317 



VIII. " Further observations ou the Amyloid Substance met with in 

 the Animal Economy.^' By Egbert McDonnell, M.D. Com- 

 municated by William Bowman, Esq. Received May 30, 1864. 



In the early part of last year I had the honour of making a communica- 

 tion to the Royal Society " On the Amyloid Substance of the Liver, and 

 its ultimate destination in the Animal Economy." The discussion which 

 followed the reading of this paper made it desirable that further observations 

 should be made regarding the natural history of this substance, more par- 

 ticularly with reference to its relations to the tissues of the foetus. It was 

 not possible to complete these investigations until the spring of the year 

 placed at my disposal foetal lambs, calves, &c. in various stages of develop- 

 ment. This has been the cause of the delay in forwarding the present 

 communication, for which I must apologise to the Society. 



The amyloid substance met with in the foetal tissues is in chemical com- 

 position identical with that found in the liver. Absolutely pure speci- 

 mens, prepared from each of these sources, are represented by the formula 

 C HO* 



With reference to its optical properties, it was stated in my former com- 

 munication, on the authority of French observers, that amyloid substance 

 of animal origin, like vegetable dextrine, causes the plane of polarization 

 to deviate to the right ; I must now confess that I have not been able to 

 verify this assertion. It is not possible, by any means that I have been 

 able to devise, to obtain a solution of this substance so transparent as to 

 admit of its being submitted to examination in the saccharometer. If a 

 portion of the liver of an adult animal, or of the muscular tissue or lung 

 of a foetus, be pounded to a pulp in a mortar with silver sand, and the 

 whole afterwards mixed into a paste with animal charcoal and allowed to 

 stand for some hours, and then treated with boiling distilled water and 

 filtered, the liquid thus obtained is too turbid to permit of its rotatory 

 power, as regards polarized light, being investigated. So small a quantity 

 as half a grain of pure amyloid substance dissolved in an ounce of distilled 

 water, produces in the solution a peculiar opalescent appearance. I have 

 proved by experiment that this is not due to fluorescence, but to the fact 

 that the amyloid substance has its particles merely in a state of suspension, 

 not of true solution. No trace of it will pass through a dialyzer without 

 the exercise of pressure, and the liquid thus obtained is not sufficiently 

 translucent for examination by polarized light. 



M. Charles Rouget and Professor Claude Bernard have examined the 

 tissues of the foetus microscopically, so as to determine the presence in 



* In my former communication I gave an ultimate analysis of the amyloid substance 

 of the liver, which Professor Apjohn, of Trinity College, Dublin, was good enough to 

 make for me. But the specimen which I had furnished was not absolutely pure, con- 

 taining a trace of nitrogen. The specimens from wliich the above formula is deduced 

 were pure. 



