719 



well as for (he Frog', that in all the examined iiulividiials, of one 

 species and in the same nerve, the i-ate (per nnitj of length) is the 

 same, hence independent of liie size of the body. Small differences 

 in the valnes of the rate, viz. of on an average 67.5 m. per second 

 for two men of a mean height of 1887 mm. and on an average 

 65.9 m. for two men of a mean height of J 721 mm., are neglected, 

 evidently considered as experimental errors. The mean body weights 

 of these men may be pnt at 85 and 67 kg. according to Hassing's 

 tables, ') and by means of this an exponent of relation for the 

 velocity of impulsion of 0.1007 can be calcnlated, to which, however, 

 in itself, not mncli significance shonid be ascribed. 



Of greater impoitance, for the stndj of the influence of the size 

 of the body on the rale of propagation of impnisions in homologons 

 nerves are Münnich's experiments. ') The rate (66 m. in the nervns 

 raedianns) fonnd by him for Man is in good concordance with the 

 mean rate according to Ai/;ock and the latest determination by 

 Helmhot,tz and H.axt ((U.56 m., in 1870), which speaks, indeed, 

 for the reliability of the method. The greatest importance for onr 

 snbject have, however, the determinations of the rapidity in the 

 nervns ischiadicns of some mammals, viz. three dogs of ditïerent 

 sizes and breeds, (wo cats, and a rabbit. AIüNiMCH jnstly lays stress 

 on the fact that the reliability of the lesnlts of his experiments on 

 animals mnst be greater than those of experiments on Man, where 

 the nerve cannot be laid bare. Besides, it is of importance for a 

 judgment of the inflnence of the dimension of the nerve on the 

 rate of condnction of the nerve inflnxions that among Münnich's 

 dogs a large and a small specimen was examined, the body weights 

 of which inter se differed more than six times as much as those of the 

 (all and the short individuals examined by AixocK. Münnich found 

 nol inconsiderable deviations between a large and a small dog, with 

 which the breed had nothing to do, and a particularly important 

 deviation in a re|)resentative of the so remarkable breed of Dachs- 

 hunds. Also the rapidities found for cats are of great importance. 

 Though Münnich himself, not realizing (hat the found numerical 

 differences could have any meaning, leaves undecided whether they 

 rest on different rates of conduction or are only caused by the 

 defectiveness of the method, it has now been raised above doubt, 



1) H. ViERORDT, Anatomische, physiologische und physische Dalen und Tabellen. 

 3 Aufl. 1906, p. 589. 



■-) t'ERDiNAND MiiNNiCH, Ueber die Leitungsgeschwindigkeit im motorischen 

 Nerven bei Warmbliitern. Zeitschrift fur Biologie. Bd. 66. Miinchen nnd Berlin 

 191B, p. 1—22. 



