io8 THE CHEMISTRY OF THE TISSUES AND ORGANS. 



stated by Berzelius, 1 Du Bois-Reymond, 2 Kiilme, 3 and Heidenhain. 4 It 

 may be readily detected in an ethereal extract by Uffelmann's reaction. 5 

 Lactic acid is formed, not only after death, but also on activity 

 during life : it is doubtless one of the acid products the accumulation 

 of which produces fatigue? though the possibilities of basic products 

 being also produced and causing fatigue by their influence on the 

 central nervous system should not be overlooked. 7 



A number of recent researches have, however, thrown doubt on the ques- 

 tion whether any free lactic acid is actually formed under these circumstances. 

 In determining this question, it is very important to know the indicator 

 employed in the investigation ; but even with the same indicator the results 

 obtained by different workers are sometimes discordant. One of the best 

 indicator? for detecting weak acids iphenolphtalein. 



Moleschott and Battistini 8 found a rise of acidity during rigor, while 

 Blome 9 did not. Warren 10 finds in fatigue that the acidity is increased, 

 but that the number of acid molecules is diminished. This is explained by 

 supposing that in resting muscle the anhydride, and in contracting muscle 

 the free acid, is present, which latter combines with twice as much base as 

 the anhydride. 



Gleiss n agrees with the generally accepted view, that the acidity of contract- 

 ing muscle is due to lactic acid, and finds that the slowly contracting red 

 muscles of the rabbit, or the very slowly contracting muscles of the tortoise, 

 become acid less rapidly than ordinary voluntary muscles. 



Weyl and Seitler l ' 2 were the first to point out that the increase of acidity 

 may be at least in part due to acid potassium phosphate, produced from the 

 alkaline phosphate by the development of new phosphoric acid from organic 

 compounds, like lecithin and nuclein. Irisawa 13 takes a similar view in 

 reference to the acidity of dead organs like the liver and pancreas. The 

 most careful work in this direction, however, is that of Rohmann. 14 He used 

 lacmoid and turmeric as indicators, and found that fresh muscle is alkaline to 

 lacmoid, and neutral or weakly acid to turmeric. During tetanus and rigor, 

 the alkalinity to lacmoid decreases, and the acidity to turmeric increases. He 

 attributes the acid reaction to monopotassium phosphate (KH 2 P0 4 ), and 

 the alkaline reaction to dipotassium phosphate (K 2 HP0 4 ), and to sodium 

 bicarbonate. If lactic acid is formed, none is free. He admits that ether 

 will extract lactic acid from muscle, but it will do so from alkaline muscle, 

 and is produced by monopotassium phosphate turning it out of combination 

 during the process of extraction. 



With regard to the origin of lactic acid, 0. Nasse believes it comes 

 from the glycogen. This is the simplest view of the matter to take, 

 and it is supported by some work of Ekunina. 15 Many facts, however, 

 do not fit in with this explanation ; and the view very generally held 



1 "Lehrbucli d. Chem.," vol. vi. p. 557. 



2 "Gesammelte Abhandl. zur allgemein. Muskel mid Nerven Physik," Leipzig, 1877. 



3 "Untersuch. ii. das Protoplasma," Leipzig, 1864. 



4 " Mechanische Leistung," Leipzig, 1864, S. 143. 



5 A dilute solution of ferric chloride and carbolic acid, which is violet, is turned yellow 

 by a trace (1 in 10,000) of lactic acid (Ztschr. f. klin. Med., Berlin, Bd. viii. S. 392). 



(i Ranke, "Tetanus." Leipzig, 1865, p. 350. 



7 A. Mosso, Trans. Internat. Med. Cong., Berlin, 1890. 



8 Arch. ital. de. biol., Turin, vol. viii. p. 90. 



9 Arch. /. cxper. Path. u. PharmakoL, Leipzig, 1890, Bd. xxviii. S. 113. Blome's 

 results have been much criticised by Rohmann ; Arch. f. d. yes. Physiol., Bonn, 1892, Bd. 

 1. S. 84, ibid.. 1893, Bd. Iv. S. 589. 



10 Arch.f. 'd. ges. Physiol., Bonn, Bel. xxiv. S. 391. n Ibid., Bd. xli. S. 69. 



12 Ztschr. f. physiol. Chem., Strassburg, Bd. vi. S. 557. 13 Ibid., Bd. xvii. S. 340. 



14 Loc. cit. 15 Journ.f. prakt. Chem., Leipzig, N.F., Bd. xx. 



