FURTHER OBSERVATIONS ON THE NERVOUS SYS- 

 TEM OF THE AMERICAN LEOPARD FROG (RANA 

 PIPIENS) COMPARED WITH THAT OF THE 

 EUROPEAN FROGS (RANA ESCULENTA AND RANA 

 TEMPORARIA) 



HENRY H. DONALDSON 



Professor of Neurology at The Wistar Institute 

 WITH TWO FIGURES 



In a paper under the general title given above (Donaldson 

 '08) I discussed some observations made in 1904 on R. esculenta 

 at Zurich and R. temporaria at Liverpool. 



On comparison with the American frog, R. pipiens, it was found 

 that although the European species were very similar to the 

 latter in form and proportions, nevertheless the weight of the 

 central nervous system was significantly smaller in the European 

 species, and in the case of R. esculenta, the number of medullated 

 fibers in the spinal nerves was much less than in R. pipiens. 



These observations made it possible to correct the records 

 of Fubini ('81) on the weight of the brain and spinal cord, which 

 had alone been available for the European forms, and to call 

 attention to the possible bearing of the anatomical differences 

 on physiological results obtained from the two European species 

 on the one hand, and the American species on the other. 



In view of the fact that on the basis of rather few observations 

 I had ventured to designate Fubini' s records as untrustworthy, 

 and also to suggest possible physiological differences in the 

 responses of the central nervous system, it seemed desirable to 

 repeat the observations on the European forms. 



This I did during the past summer. For a second time I am 

 indebted to Professor Gaule for the hospitality of the Physio- 

 logical Institute at Zurich, where I had examined R. esculenta in 

 1904, and to Professor Sherrington for similar privileges at the 



