544 Mr. Foster on Glycogen in Entozoa. [Dec. 7, 



By mincing and boiling in water, with a drop of dilute acetic acid, one 

 of these animals, a decoction is obtained which remains milky-looking 

 and opalescent after several filtrations, -and therefore at once suggests the 

 idea of glycogen. This milky fluid strikes a deep port-wine red with 

 iodine, the colour disappearing on the application of heat, and reappearing 

 on cooling, and gives no reduction when boiled with the alkaline copper- 

 solution. When treated with saliva at 35 C. the opalescence disappears, 

 leaving a fluid either perfectly clear or exhibiting only a few flakes or a 

 slight cloudy deposit (of some albuminoid material), but containing much 

 sugar, as may be shown both by the copper and fermentation test. 



If the original milky fluid be thrown into spirit, an abundant Avhite 

 flaky precipitate is thrown down, consisting partly of some albuminoid 

 substance, but chiefly of a substance giving all the above reactions of 

 glycogen. If the fluid be thrown into glacial acetic acid, a white flaky 

 precipitate is thrown down consisting of nearly pure glycogen. The pre- 

 sence of glycogen may also be shown by employing the alcoholic solution 

 of potash. From these facts we may infer that glycogen, and not dextrine 

 merely, does exist in the bodies of these animals. 



In no case have I found this glycogen to be accompanied by anything more 

 than a mere doubtful trace of sugar that is to say, a trace of some substance 

 giving a doubtful reduction of the copper-solution, and that by no means 

 always. Hence, seeing how difficult it is to obtain glycogen in so pure a 

 state that its quantity may be estimated directly by weighing, I have con- 

 tented myself with determining the amount present in these animals by 

 exposing a decoction to the influence of saliva until all traces of glycogen 

 were lost, and then estimating by the copper process the amount of sugar 

 produced. In this way I obtained from two ascarides weighing together, 

 when taken fresh from the pig. and merely wiped, 10'2 grms., and from 

 three weighing together 10 grms.j just 2'2 per cent, of sugar (on the wet 

 weight) in each case. When this amount is compared with that produced 

 by the mammalian liver alone, it will be seen that it really is, compara- 

 tively speaking, excessive. For the sake of comparing the Ascaris with 

 other invertebrata, I may say that in a caterpillar weighing about 6 grms. 

 I obtained a hardly appreciable quantity of glycogen, which was contained 

 partly in the muscular parietes, and partly in the so-called "epiploon" or 

 " hepatic parenchyma." The quantity, of glycogen that I obtained from 

 a handful of common maggots was also hardly appreciable. 



In the Ascaris little or no glycogen js to be found in the intestine, a 

 small quantity in the generative apparatus, and a very considerable quantity 

 in the spongy visceral tissue ; by far the largest amount exists in the firmer 

 muscular parietes. I failed to detect with iodine any distinct histological 

 localization. 



It seems singular that an animal, living in the midst of a fluid one of 

 whose chief functions is to change starch into sugar, should thus be found 

 amassing glycogen within its own body. I have satisfied myself, however, 



