REGENERATION IN LARVAL LEGS OF SILKWORMS. 



VERNON L. KELLOGG, 



Stanford U ni-jersity, California. 



With 10 Figures. 



As far as mentioned by Morgan^ and Brindley,^ which are the 

 only two recent accounts, known to me, that attempt to refer in an 

 inclusive way to the recorded observations and experiments on 

 regeneration in insects, alP the work done on regeneration of the 

 legs in insects with complete metamorphosis has been limited to 

 making mutilations of the larval legs and noting what, if any, 

 effect was apparent in the legs of the imago. There are several 

 accounts of such observations, and some of these accounts 

 are, curiously enough, of comparatively recent date. I say 

 "curiously," for it has been known now for a score of years and 

 more, that the legs (as also the wings, antennae, etc.,) of insects 

 of complete metamorphosis are derived (at least in all the higher 

 forms, such as the Lepuiop>.tera, Dtptera and Hymenoptera) not 

 by a transforming of the larval legs (if present) into the imaginal 

 ones, but from new centers called imaginal discs or histoblasts. 

 These histoblasts are developed from an invagination of the larval 

 cellular skin layer (hypoderm) and only in comparatively late 

 larval life do the new developing imaginal legs lie within the larval 

 ones. It follows from this that if a larval leg be cut off in early 

 larval life the imaginal leg is in no way mutilated, and that if it 



'Regeneration, 1901. 



^On Certain Characters of Reproduced Appendages in Arihropoda, particularly 

 in the Blattidce. Proc. Zool. Soc, Lond., 1898, pp. 924-958. 



■''Tornier describes (Zool. Anzeiger, Vol. XXIV, pp. 634-664") certain experiments 

 on regeneration in the meal beetle, Tenebrio molitor, in which account he states that 

 cut-off larval legs are regenerated before pupation, if young larvas are used as 

 subjects. This statement of Tornier's I have only found since sending my paper to 

 press. 



