723 



From the inucli older records of Kaiser it may be derived that the 

 exponent of relation for the volume of the largest ganglion cells of 

 the cervical medulla of the much larger Bat Plecotus auritns is 

 only 0.1568 in comparison with the Mole ^). This Bat has, accord- 

 ingl}^ a much larger ganglion cell than the Mole, in ratio of eqnai 

 body weight. Obkkstkinkr points out that Man and the Orang-outang 

 have striltingly small cells in their cervical medulla"). 



According to Hardesty's measurements homologous cells of the 

 cervical intumesccntia of Man are actually somewhat smaller than 

 in the Foxhound, which he exceeds four times in body weight '), 

 and not much larger than those of the Cat, which he exceeds more 

 than twent}^ times in body weight. As well for Macacus, Cynoce- 

 phalus, Ateles as for Man, the nerve tibers of the plexus brachialis 

 are thin, in comparison with those of other Mammals, the size of 

 tlie body being taken into consideration. 



Evidently the slight quickness of the muscles, but comparative 

 delicacy of the muscle fibers for the hand and the lingers, as neces- 

 sary factor for their finely regulated collaboration, may be imputed to 

 the slight thickness of the nerve fibers and the comparatively 

 small volume of the ganglion cells, with which they are 

 connected. 



The dimensions of the peripheral "conductors" and of the central 

 "accumulators", connected with them, can become of great importance 

 for the quantity of the brain. Where they are to supply muscles which 

 are both strong and quick, the nerve fibers become particularly 

 thick, the cell-bodies large, and thus the neurones voluminous, to 

 which also voluminous brain neurones must answer. Of the problems 

 of the Elephant having a more voluminous brain than the Anthro- 

 poid Apes, to which it was thought that an extraordinary mental height 

 had to be attributed for this reason, of the Ateles and Cebus, 

 equally high above the Anthropoids with respect to their quantity 

 of brain, of the aquatic Mammals, among which the Mysticetes 

 possess comparatively larger brain than the Dogs, of the Denticetes, 

 which like the Seals can almost be put on a line with the Anthro- 



') 0. Kaiser, Die Funktionen der Ganglienzellen des Halsmarkes. Haag 1891, p. 63. 



*) L. c. p. 4. The same properly may be assumed for the Gorilla, whose spinal 

 cord was examined by W. Waldeyer (Das Gorilla-Riickenmark. Abhandlungen 

 der Kön. Preus. Akademie der Wissenschaften Berlin. Jahr 1888. Physikalisch- 

 matbematische Classe. Abl. ill, S. 1 — 147). Gf. Hardesty, I.e., p. 168. 



3) Gavazzani (1. c, p. 52 and 53) had already found that the ganglion cells in 

 Man are smaller than in Shepherd's Dogs and Pointers, smaller even than in 

 the Gat. 



47* 



