i 7 4 SCIENCE PROGRESS 



Ohrwall, Skand. Arch.f. Physiol. 7, p. 222 (1897). 



Pfluger, Pftiiger>s Arch. 6, p. 43 (1871) i 10, p. 251 (1875) ; 14, p. 5 (1878). 



Spiro, Zeit.f.physiol. Chem. 1, p. m (1878). 



THUNBERG, Skand. Arch.f. Physiol. 17, p. 133 O^S)- 



VERWORN, Arch.f. {Anat. u.) Physiol. (1900), Suppl. p. 152 ; also "Die Biogen- 



hypothese" (Jena, 1903). 

 Vernon, fourn. Physiol. 35, p. 53 (1906); Zeit. f allgem. Physiol. 6, p. 393 



(1907). 

 Winterstein, Zeit.f allgem. Physiol. 6, p. 315 (i9°7)- 



