NERVOUS SYSTEM OF THE FROG 



9 



vations made at the contrasted dates, and that in both instances 

 the proportional lengths are nearly the same for the three species 

 compared. 



TABLE 8 

 The proportional lengths of the several leg bones 



FOOT 

 (TARSUS 

 AND PES) 



R. pipiens 1904 



R. pipiens 1909 



R. esculenta 1904*. . 

 R. esculenta 1909. . . 

 R. temporaria 1904* 

 R. temporaria 1909. 



per cent 

 29.3 

 29.3 

 28 . 2 

 28.2 

 28.7 

 28.3 



per cent 

 45 . 2 

 44.7 

 45 5 

 45 . 

 45.2 

 46.0 



* Leg bones from frogs of the socalled "Zurich series of 1898." These frogs had been carefully fixed in 

 4% formaldehyde and then preserved in 80"^, alcohol. The effect of this on the lengths of the several leg 

 bones was not at the time determined. (See Donaldson '08, p. 127). 



(D) PERCENTAGE VALUE OF THE LENGTH OF THE ENTIRE CEN- 

 TRAL NERVOUS SYSTEM— THE TOTAL LENGTH OF THE FROG 

 BEING TAKEN AS THE STANDARD. 



In the case of this character we have grouped the 1904 data 

 (see Donaldson '08, table 5) into three entries and added the 

 measurements on the new material for the 1909 groups. 



The table shows that the length of the entire central nervous 

 system is slightly greater in the European species. As this excess 

 in length is associated with a deficiency in absolute weight, it 

 follows, as was previously noted (Donaldson '08, p. 128) that the 

 nervous system in R. pipiens must exceed that of the European 

 species in its transverse diameters. 



