84 Process of Reproduction of the 



the centre of the cylinder or tube. The same explanation evidently 

 applies to these, as to the stalactites of Delvine. With respect to 

 the central cavity, it is analogous to that which so often occurs in 

 ordinary calcareous stalactites, and presents no further difficulties. 

 I may add respecting these, that as the sand is generally fer- 

 ruginous, they are commonly of a brown colour and much charged 

 with th° -ust of iron. 



Art. VIII. On the Process of Reproduction of the Members 

 of the Aquatic Salamander. By Tweedy John Todd, M.D., 

 F.R.M.S.E., 8sc. 



Section 1st. Description of the Process in general. 

 The reproduction of the members of the Aquatic Salamander 

 may, perhaps, be better understood by considering it as consisting of 

 three distinct subordinate processes, viz., of growth, organization, 

 and increase. That of growth may be described as the production 

 of a homogeneous substance, of the nature of coagulable lymph, of 

 the form, but of a much smaller size, than the original member ; 

 that of organization, as the conversion of this substance into the 

 different structures, which naturally constitute the member ; and 

 that of increase, as its slow and gradual progress to the size of the 

 original part. 



When the limbs of the salamander are removed, the phenomena 

 of inflammation and its terminations present themselves as in all 

 the other vertebral animals ; nor until the cicatrix is completely 

 formed can any difference be observed in either case, except that 

 the extremity of the stump, which in other animals tapers and 

 assumes a conical form, in this becomes enlarged and bulbous. 

 This swelling of the stump generally precedes the formation of the 

 cicatrix. It, however, sometimes coincides with it, and very rarely 

 follows it. I have observed, when the cicatrization is protracted, 

 the swelling of the stump precedes the cicatrix a considerable 

 time, as much as fourteen days, and, when it is accelerated, they 

 generally take place together. In some rare cases the tumefaction 



