43 



celtis has a shortened wing due to an antenna having fallen over it at 

 pupation. In itself this wing is on all fours with the P. palpina 

 already referred to. As a rule, one may perhaps assume' that where 

 the alteration is symmetrical, affecting both sides, it is congenital, but 

 this will not hold good always, as, for example, in symmetrical results 

 of undue pressure by the girth in Papilionidce, etc. 



By a very instructive examination which Mr. Bateson makes of 

 the morphology of duplicated appendages, he proves that in a large 

 proportion of cases the relationship of the extra parts is of a definite 

 character, e.g.'iia. limb has three parallel tarsi, each of these is like 

 its neighbour, but its neigiibour reversed as if seen in a mirror. The 

 exceptions are, however, rather numerous. This peculiar law as to 

 reduplicated parts does not seem to tiirovv any light on the question 

 as to whether such developments are congenital or a result of 

 regeneration, but is probably connected with the view of germ-plasm 

 I have accepted, viz. that until it begins to develo[), it is not 

 specially ear-marked, but takes its line of progress by reference to its 

 surroundings. 



My own opinion is that a very large proportion of malformations of 

 antennse, palpi, legs and wings in Lepidoptera (and other insects) 

 is the result of regeneration taking place in an abnormal manner. 



Bateson refers to Roesel's opinion that malforuiations of claws of 

 Crustacea were due to injury, with or without regeneration, and notes 

 that others have held this view ; he says there is no ground for this 

 opinion, and that it further happens that the whole of an injured 

 limb is usually thrown off in Crustacea, so that injury to the claws 

 cannot cause such abnormalities. I know too little about Crustacea 

 to discuss this profitably, but I may suggest that the germ-plasm of 

 the regenerative centre might be injured, or the new limb might 

 suffer from injuries, the result of the old limb being thrown off. 



Lepidoptera, however, are on a somewhat different horizon, and 

 there is some evidence that such malformations originate in faulty 

 regeneration. Apart from any evidence, it is pertinent to note that 

 a regenerated limb is developed de ?iovo from germinal material, and 

 must be quite as liable to malformation as any other limb, but more 

 particularly the reserved germinal material has a somewhat different 

 history from that which primarily developed into the limb, and, if one 

 may so express it, it has had less experience in the business, and is 

 thus more likely to yield to disturbing influences. A very important 

 point is also that the germinal matter of the regenerative centre 

 is very apt itself to suffer when the accident, whatever it may be, 

 happens — to suffer mechanically, chemically, or in both ways ; what 

 is especially to be considered is that it may be divided into several 

 portions, which may not reunite, but each undergo development apart 

 from its fellows. The not very rare cases of lizards with double or 

 even triple tails are, I believe, admitted to be the result of an 

 anomaly of regeneration, and appear to me to be on all fours with 

 the great majority of cases of reduplicated appendages in insects. 



