92 Process of Reproduction of the 



sion, but must arise from something peculiar in the influence of the 

 nerve. I must, however, observe the same uniform influence was 

 not observed in every part. The intersection of the spinal marrow 

 at the origin of the tail had no power of checking its repro- 

 duction. 



Section 3d. Comparison of the Process of Reproduction in dif- 

 ferent A nimals possessing this poiver. 



In reasoning on the phenomena of reproduction, the compari- 

 son of this process, in the different animals endued with it, natu- 

 rally presents itself to the mind as a method by which further 

 knowledge of the process may be obtained. 



In the tadpoles of the frog and toad the process is precisely the 

 same as in the lava of the salamander. But except in the repro- 

 duction of the tail, which is both constant and vigorous, it is very 

 uncertain in its extent, and strictly confined to certain states of 

 developement, the absorption of the tail distinctly marking the 

 period when the power is entirely lost. It is, however, curious to 

 observe to how near the moment of metamorphosis the reproduc- 

 tion of the tail continues. 



I have ascertained that the reproduction of the tail of the lizard 

 is effected by the same process as that of the salamander, and, I 

 should think, from what may be collected from Reaumur's obser- 

 vations, it is probably the same in the crayfish and its species. 

 In the snail I have also every reason to believe the same process is 

 observed. 



From the very interesting experiments of my ingenious frieud, 

 Professor San Giovani, of Naples, I am authorized to conclude, 

 that although the reproduction of the earth-worm presents some 

 specific differences, yet the general process is the same. I am 

 entirely indebted to his liberality for the following account of it. 

 When earth-worms are divided at the lower edge of their great 

 ring, if they survive the injury, which they generally do three in 

 twenty times, the separate parts gradually diminish in circumfer- 

 ence, the wounds cicatrize, and the cicatrix, which is of a bright 

 red colour, is surrounded by a round projecting band, (bonrrelet.) 



