Fortpflanzung. 331 



tation in complete or incomplete tetanus increases the heat production. When 

 tlie tetanus is complete the value of the ratio of the heat produced to the tension 

 developed is independent of the frequency of excitation. The tension development 

 and (initial) heat-evolution are products of the same reaction. Mines. 



847) Fletcber, W. M., Lactic acid formation, survival respiration and 

 rigor mortis in mammalian muscle. In: Journ. of Physiol., Bd. XL VII, 

 S. 361, 1913. 



Rabbit's muscle immediately after excision contains very little lactic acid. 

 The lactic acid increases rapidly after excision, approximately equal amounts 

 being formed in equal times: a maximum is reached soon after the third hour. 

 The acid production is slower in red than in white muscle. In the case of white 

 muscle fibres at body temperature the rate of CO2 Output increases for a time 

 after excision and then falls until the onset of putrefaction. Red muscle fibres at 

 all temperatures tried, and white muscle at room temperature gave decreasing 

 amounts of COg from the time of excision. The survival yield of CO2 is ac- 

 counted for by the action of the lactic acid formed on carbonates already present 

 in the muscle. 



The onset of rigor mortis in white and red muscle is described and the 

 differences observed are discussed. Mines. 



848) Langley, J. N., The protracted contraction of muscle caused by 

 nicotine and other substances chiefly in relation to the rectus ab- 

 dominis muscle of the frog. In: Journ. of Physiol., Bd. XL VII, S. 159, 1913. 



There is a wide difference in the concentration of nicotine required to cause 

 contraction in the neural (0,OOOl7o) and non-neural (> 0,1%) regions of the rec- 

 tus abdominis. A stronger Solution of nicotine (l7o) causes a strictly local con- 

 traction in the non-neural region. An extract of the unstriated muscle of the 

 stomach caused slight contraction of the rectus abdominis: extracts of other 

 tissues had no constant effect. A distinction is drawn between contraction and 

 contracture. Contraction lasts only during the continued presence of some che- 

 mical substance : contracture persists after the substance provoking it is removed. 



Mines. 



Fortpflanzung. 



'''^849) Champy, Chr., Recherches sur la Spermatogenese des Batfaciens 

 etles Clements accesso ir es du testicule. In: Arch. de Zool. Exper. et gen. 

 Bd. 52, Heft 2, S. 13 — 304, 1913. 



L'important travail de Champy etant uue mise au point complete de la 

 question de la Spermatogenese chez les Batraciens, constitue une revue critique 

 de tous les faits connus relatifs au probleme, revue eclairee par les recherches de 

 l'auteur qui apportent des faits nouveaux, ou des interpretations personnelles. 

 Champy examine d'abord l'origine des cellules germinatives et accepte les 

 conclusions de Dustin (1907), mais il n'admet, contrairement ä cet auteur, que 

 la formation d'une seule lignee de gonocytes aux depends de l'ebauche prim- 

 ordiale. II examine ensuite la structure des gonies primitives et decrit avec soin 

 leur structure intime: chondriome, grains osmioreducteurs, grains colorables par 

 les colorants vitaux, corps chromatoides ou pyrenoides, centrosome, noyau lobe ou 

 incise; il pense que ces cellules ont une activite elaboratrice propre. Vient ensuite 

 l'etude des gonies de 2^°^® ordre, puis celle des cytes et des deux divisions, de 



