Henky H. Donaldson 15 



C.N.S. = (Log W X 1^ i) 28. 



This formula is similar to that for the bullfrog, except as regards the constant, 

 which for the leopard frog is 28. 



BIBLIOGRAPHY 



Donaldson, H. H., 1898. " Observations on the Weight and Length of the Central Nervous 

 System and of the Legs in Bull-Frogs of Different Sizes." Journal of Comparative Neurology, 

 VIII (1898), pp. 314-35. 



Donaldson, H. H., and Schoemakeb, D. M., 1900. "Observations on the Weight and 

 Length of the Central Nervous System and of the Legs in Frogs of Different Sizes (Rana 

 virescens brachycephala — Cope)." Journal of Comparative Neurology, X (1900), pp. 109-32. 



DuBois, E., 1898. " Ueber die Abhangigkeit des Hirngewichtes von der Korpergrosse bei 

 den Saugethieren," Archiv fur Anthropologie, XXV (1898), pp. 1-32. 



Snell, O., 1892. "Die Abhangigkeit des Hirngewichtes von dem Korpergewicht und 

 den geistigen Fahigkeiten." Archiv fiir Psychiatrie und Nervenkrankheiten, XXIII (1892), 

 pp. 436^6. 



EXPLANATION OF FIGURE I 



For this figure the data in Tables I and IV have been employed, and the accuracy of the 

 figure can be tested by comparison with the tables. 



The divisions on the base line indicate grams of body- weight; the divisions on the ordi- 

 nates, milligrams of weight of the central nervous system. The observed weight of the central 

 nervous system in milligrams is marked by + on the line of the ordinate above the point on the 

 base line corresponding to the body-weight of the frog from which the central nervous system 

 was taken. The calculated weight of the central nervous system is marked on the same ordinate 

 line by a black dot (.). So far as it could be done without confusion, the (.) black dots indicat- 

 ing the calculated weights have been joined by a line, to better indicate their general relation to 

 the observed records. The whole chart for the leopard frog has been shifted in the figure along 

 the base line 50 grams to the right ; hence all the body- weights in this chart are to be reduced 

 by 50 grams from the weight indicated by their position. 



In plotting the records, the indications (. and +) have been placed exactly where they 

 belong except in those cases where exact placing would cause them to overlap. In such 

 instances the displacement necessary for clearness has been distributed among the several 

 records. In no case, however, does this displacement modify in any essential feature the char- 

 acter of the chart. 



29 



