158 THE BLOOD. 



in plasma, namely (1) glycogen ; (2) an animal gum ; (3) dextrose or 

 grape sugar. 



1. Glycogen. There seems to be no doubt that traces of glycogen can 

 be obtained from fresh blood. Some is said to occur free in plasma, but 

 if so it is probably derived from intermixed or disintegrated leucocytes, 

 which can be shown by histochemical reaction to contain it. 1 Kaufmann 

 finds the amount of glycogen in blood to be greatly increased (from 0*025 

 to 0*59 per litre) by removal of the pancreas. 2 



2. Animal gum. Freund 3 has obtained from blood a carbohydrate 

 substance, resembling that described by Landwehr under the above name. 

 It has the formula (C 6 H 10 5 ) n , and is converted by boiling with dilute 

 mineral acids into a substance (sugar) which reduces Fehling's solution, 

 but is not fermentable, nor is it rotatory for polarised light. Four litres of 

 ox blood yielded 0'82 grms. of the gum, giving a percentage amount of 0*02. 



3. Dextrose. This is a constant constituent of plasma, whatever the 

 nature of the diet, and even in starving animals. 4 It occurs in man to 

 the amount of about 012 per cent, of the blood, in the dog from Oil 

 to 015 per cent, (or a little over 1 per 1000). 5 It is present in 

 nearly equal amount in blood from all parts, except in the blood of the 

 portal vein, during digestion of carbohydrate-containing foods, where 

 it is markedly increased. In the blood of the hepatic veins, in the 

 intervals of digestion, the amount was stated by Bernard to be some- 

 what greater than in the portal vein, or in the blood of the general cir- 

 culation ; but this difference has not been found by Pavy and most other 

 observers, although the statement has of late been reaffirmed by Seegen. 6 



Bernard 7 obtained a larger amount of sugar from arterial than from 

 venous blood, and Seegen has in some instances obtained a similar 

 result. Chauveau, 8 and Chauveau and Kaufmann, 9 have also published 

 analyses, which seem to show a disappearance of sugar after passing 

 the capillaries. But the differences observed have not been constant, 

 and are in any case so small as to lie within the range of experimental 

 error. As the result of eleven experiments, Pavy finds the sugar in 

 arterial blood to exceed that in venous by only 0*003 parts per 1000 ; 

 and he concludes that no appreciable difference exists between the two. 10 



1 E. A. Schafer, "A Course of Practical Histology," London, 1876, p. 39; Salomon, 

 Deutsche med. Wchnschr., Leipzig, 1877, S. 92 and 421 ; Arch. f. Physiol., Leipzig, 1878 ; 

 Oentralbl.f. Physiol., Leipzig u. Wien, 1892, Bd. vi. S. 512 ; Ehiiich, Ztschr.f. klin. Med., 

 Berlin, 1883, Bd. vi. S. 40 ; Gabritschewsky, Arch. f. exper. Path. u. Pharmakol., Leipzig, 

 1891, Bd. xxviii. S. 272; Huppert, Centralbl. f.' Physiol, Leipzig u. Wien, 1892, No. 

 14, S. 394 (Huppert found more in dog's blood than in the blood of herbivora) ; Hoppe- 

 Seyler, Ztschr.f. physiol. Chem., Strassburg, 1894, Bd. xviii. S. 144. 



2 Compt. rend. Acad. d. sc., Paris, 1895, tome cxx. p. 567. 



3 Centralbl. f. Physiol., Leipzig u. Wien, 1892, Bd. vi. S. 345. 



4 01. Bernard, Arch. g6n. de med., Paris, 1848, tome xviii. p. 303; Pavy, Phil. Trans., 

 London, 1860 ; v. Mering, Arch. f. Physiol., Leipzig, 1877, S. 379 ; Otto, Arch. f. d. ges. 

 PhysioJ.. Bonn, 1885, Bd. xxxv. S. 467; Pickardt, Ztschr. f. physiol. Chem.. Strassburg, 

 Bd. xvii'. S. 217; Miura, Ztschr.f. Biol., Miinchen, Bd. xxxii. S. 255. 



5 Pavy, "Physiology of the Carbohydrates," 1894, p. 161. 



6 Arch. f. d. ges. Physiol., Bonn, 1884, Bd. xxxiv. S. 388, and 1885, Bd. xxxvii. S. 

 348; CentralU. f. Physiol., Leipzig u. Wien, 1893, No. 12; " Zuckerbildung im Thier- 

 korper," 1890. 



7 Compt. rend. Acad. d. sc., Paris, tome Ixxxiii. p. 373, and "Leconssurle Diabete," 1877. 



8 Ibid., 1856, tome xliii. p. 1008. 



9 Ibid., 1886, tome ciii. p. 974. 



10 Pavy, Proc. Roy. Sac. London, 1877, vol. xxvi. p. 346 ; "On Certain Points connected 

 with Diabetes," London, 1878 ; "Physiology of the Carbohydrates," pp. 170-171. This 

 is also apparently admitted by Seegen ("La Glycogenie Animale," Paris, 1890, p. 100), 

 although his theory of the production of energy requires that there should be a diminution 

 in the amount of sugar in venous blood. 



