Mr Brindley, Note on Abnormalities of Dipnoan Fishes. 327 



seems almost certainly in some instances to be the healing tissue 

 of a wound assuming a special form and conspicuous dimensions, 

 thus forming a new tail springing from the side of a normal one. 

 Where the new growth is bifid from its commencement we have 

 also sprouting from a wounded surface,' that is, the origin of the 

 growth differs only in position from the above. In the de- 

 velopment of a normal limb or tail the growth proceeds with 

 that of the whole animal, but in the repair of an injury there is a 

 special proliferation at one point and the epidermis makes haste 

 to cover the subjacent tissues exposed at the end of the stump. 

 Thus the trophic events of growth proceed otherwise than in 

 normal development and with the immediate purpose of covering 

 the wound, while at the same time there is unusual exposure to 

 accidental interference from external influences, such as contact 

 with foreign bodies. Under these circumstances it seems not 

 impossible that extremely slight circumstances of the moment 

 may affect the direction of growth of the rapidly-extending epi- 

 dermis without checking the growth as a whole in its endeavour 

 to cover the wound, or the subjacent tissues might be interfered 

 with before they were covered over. So in the absence of the 

 coordination of growth holding in normal development external 

 interference might in some cases mould the regenerating structure 

 in a special form. The curious tendency to branch displayed by 

 the structures described is interesting, though the suggestion 

 made by one or two authors that abnormalities of this kind may 

 have some phylogenetic importance appears to rest on doubtful 

 grounds. The branched condition seems more probably explicable 

 on the strength of accidental and local influences. 



24—2 



