200 RE GENERA TION 



form sarcoblasts ; and these pass into the new part, where they make 

 the new muscle fibres in the same way as do the cells of the embryo. 

 In older larvae of the frog, and in mature animals in general, the 

 changes are more complicated. Two processes can be distinguished: 

 (a) degenerative and (b} regenerative, (a) Broken-down muscle 

 fibres that have been cut, and torn-off pieces of muscle fibres, are 

 found present. There follows an accumulation of leucocytes and of 

 giant cells. The nuclei in the degenerating muscle fibres atrophy, 

 and the substance of the fibres breaks down, (b) The muscle fibres 

 split lengthwise to form spindle fibres, and there is an increase in the 

 number of nuclei at the same time. Sarcoblast-like outgrowths of the 

 old muscle fibres are formed, which produce the sarcoblasts that 

 become new muscle fibres. 



Barfurth agrees with Fraisse in two main points, viz. that all the 

 tissues of the tail have the power of regeneration, and that each tissue 

 produces only tissue like itself. The law which Kolliker attempted to 

 establish, viz. that the elements of the formed tissues have lost the 

 power of producing other kinds of tissue, the law of the specification 

 of the tissue, is supported by these results of Fraisse and of Bar- 

 furth, but is contradicted, as has been shown above, by the results on 

 the earthworm, and also as we shall see even in the amphibia, as for 

 instance in the regeneration of the lens of the eye. 



Spallanzani 1 was the first to study the regeneration of the 

 limb in salamanders, and found that the skeleton in the new part is 

 like that in the normal limb. Bonnet, Philipeaux, 2 as well as other 

 naturalists, 3 also examined the regeneration of the limbs of salaman- 

 ders. Gotte ('79) has studied the embryonic development and the 

 regeneration of the limb of triton, especially in regard to the origin 

 of the new bones. He found that the skeleton develops in much the 

 same way in the embryonic limb and in the regenerated limb, and the 

 process in the latter may be said to repeat that in the former. This 

 is especially true for the regeneration of the limb of a very young 

 larva, but the older the larva the more it departs from the embryonic 

 type of development. If the limb is cut off through the upper arm, 

 or through the thigh, new tissue develops over the cut-end. If the 

 larva is quite young, so that formation of the cartilages in the leg has 

 not gone very far, the new tissue differs very little from the old ; but 

 if the leg of an older larva is amputated, the difference between the 

 old and the new parts is more striking. If the bones of the leg have 



1 Prodrome, 1768. 



2 Philipeaux, Comptes rendus de I'Acad. des sciences de I'Institut de France, Annee 

 1866, 1867. 



8 Todd (Quarterly Journal of Science, Literature, and Arts, Vol. XVI), Blumenbach, 

 Treviranus, Von Siebold. 



