MOTOR NUCLEI IN PHYLOGENY 469 
It is a pleasure for me to acknowledge my indebtedness to 
Dr. Kappers, as well for his help and the stimulating interest 
he took in my work as for the generous way in which he placed 
the resources of his laboratory at my disposal. 
With regard to my material, the present work is based upon 
the special study of the motor nuclei in the following represen- 
tative forms: Bdellostoma dombeyi, Selache maxima (Ceto- 
rhinus maximus), Polyodon spathula, Ameliurus nebulosus, 
Solea vulgaris, Rana catesbeana (mugiens), Damonia_ sub- 
trijuga, Cacatua roseicapilla, Hypsiprimnus murinus and Pan 
satyrus (Troglodytes niger). In addition, Hexanchus, Hep- 
tanchus, Ciconia alba and Vesperugo noctula were re-studied, 
though the motor nuclei in these forms had already been charted 
and recorded elsewhere.’ 
The specimens of Polyodon spathula were obtained through 
the courtesy of Prof. R. J. Terry of Washington University, St. 
Louis, and I am also much indebted to Prof. Howard Ayers 
who very generously furnished me with specimens of Bdellos- 
toma dombeyi from his personal collection. Several of these 
brains had been fixed by him by the Cajal method, others fixed 
by different methods were subsequently stained in various ways. 
The series for the most part were cut transversely at 25 
microns. With the exception of Bdellostoma, alternate sec- 
tions in each series were arranged on celloidin films and stained 
by Pal-Weigert-carmine and van Giesson methods (Kappers, 
64). ; 
All the technical work in connection with cutting, staining 
and mounting this material, was done in the laboratories of the 
Central Dutch Institute for Brain Research and I wish to ex- 
2 The name ‘Pan satyrus’ is used here for this species of chimpanzee in con- 
formity with the recent work of the late D. G. Elliott (21). The claims of 
priority also demand the change in nomenclature from ‘R. mugiens’ to ‘R. 
catesbeana’ for the bull frog (vide Gadow, 26). In the case of the sharks Noti- 
danus cinereus and N. griseus, the old terms Heptanchus and Hexanchus re- 
spectively have been retained for convenience in description, while in the case 
of the basking shark the name ‘Selache maxima’ rather than ‘Cetorhinus maxi- 
mus’ has been used, though both seem equally in vogue (vide Jordan, 54, and 
Bridge, 12). 
