MEDICINE IN MODERN TIMES. 717 



powers of reproduction which two sets of air-breathing terrestrial 

 animals, the pulmonate snails and the earth-worms, possess, to the 

 great development of their excretory apparatus. Living, as they 

 do very ordinarily, in atmospheres laden with carbonic acid from 

 decaying vegetable matters, they must get rid of the products of 

 their waste and wear in the shape of fluid solutions ; and the alka- 

 line secretion with which the bodies of both are so abundantly 

 slimy, furnishes just the required medium. When injured or 

 mutilated, these animals can withdraw themselves pretty com- 

 pletely from the atmospheric oxygen by shedding out this secre- 

 tion, and it at the same time disembarrasses their system from any 

 excess of carbonic acid which may be generated within it. Thus 

 they can attain the most perfect possible condition for repair and 

 regeneration, the minimum of activity of all save the excretory 

 organs ; and I submit that it is possible that these two conditions 

 may be connected as cause and effect, just as in the reverse direction 

 a defeat of surgical skill may be connected with the presence of a 

 fatty kidney or liver, or the excitability of a nervous system. It 

 is going perhaps too far to attempt to explain the much greater 

 power of repair which Amphibia possess as compared with either 

 Pisces below or Reptilia above them to the larger size, and conse- 

 quent smaller aggregate surface and less perfect aerating power of 

 their blood-cells, and to the transpirability of their naked skins, 

 which execute such important depuratory work for them, and are so 

 closely connected and correlated with their lungs, livers, and 

 kidneys. It is curious, however, and interesting to remark that 

 the older anatomists, in commenting on the very obvious solidarity 

 of these latter organs, went on^ in their ignorance, I imagine, to a 

 great extent of the nature of amyloid and other degenerative 

 changes in such cases, to observe that it was illustrated by the 



* fact ' that, as the lungs grew smaller, so the kidneys grew larger 

 in phthisis^. (See Funk, 'De Salamandrae Terrestris Vita,' 1827, 

 and Meckel, 'Pathol. Anat.' vol. i. 613, 646.) 



Verloren, as quoted by Bonders (' On the Constituents of Food,' 



^ For accounts of experiments as to regeneration of lost or destroyed parts, see 

 Darwin, 'Animals and Plants under Domestication,' vol. ii. p. 15, ibique citata ; Owen, 

 *Comp. Anat. of the Vertebrata,' vol. i. p. 567; Newport, ' Phil. Trans.' vol. cxxxiv. 

 1844, ibique citata; Paget, 'Surg. Path.,' ed. Turner, p. 123; Spence Bate, 'Ann. 

 and Mag. Nat. Hist.,' August, 1868, citing Mr. Lloyd of Hamburg, p. 118 j Mcintosh, 



* Experiments on Carcinus Mcenas,' p. 28, 



