54 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I42 



antennae that gives the latter their most leghke appearance. Len- 

 gerken (1933) suggests that the apparent claws result from a split- 

 ting of the end of the flagellum. Similar processes, he says, are often 

 found on the apex of the normal antenna, and he gives a figure of 

 such an antenna in a beetle. Though the frequent occurrence of 

 claws on regenerated antennae is somewhat perplexing, before we 

 accept them as true pretarsal leg claws we should know more of their 

 structure, and of how they arise from the end of the appendage. 



Those who discount the idea that the regenerated antenna is a re- 

 version to a primitive leg, usually explain its leglike form as resulting 

 from the influence of the "leg organizer" on the newly growing tissue. 

 It is surprising, then, that the basal part of the regenerate should 

 always be that of an antenna. The various forms of normal antennae 

 (fig. 14) are produced principally by modifications of the flagellum. 

 As already noted, the flagellum of the lower insects grows by sub- 

 division of its basal section. 



It is quite impossible that the insect antenna was ever a leg in the 

 past history of the insects. The Crustacea are older than the insects, 

 and none of them has a leglike first antenna ; even in the trilobites the 

 antennae are long filaments. If the antennal "leg" regenerate is a 

 return to an ancestral form of the appendage, it would have to be a 

 throwback through millions of years before the Cambrian, long before 

 insects existed, when the arthropod ancestors very improbably had 

 fully segmented legs with paired apical claws. The antennal "leg" 

 proves too much for the theory of its leg origin, and thus gives no 

 support to the idea that the antennae are appendages of a formerly 

 postoral segment of the trunk. The claim that the antennae are modi- 

 fied, primarily postoral legs needs stronger support than that derived 

 from regeneration. 



Heteromorphic regenerates have followed even amputation of the 

 compound eyes. Experiments in eye removal on the cockroach and 

 Tenebrio larva by Janda (1913) and by Kfizenecky (1913) produced 

 only small fingerlike outgrowths in place of the amputated eye, ac- 

 companied in most cases by a small regenerated eye. On the other 

 hand, in experiments by Herbst (1896, 1900, 1902) on Crustacea, 

 the amputation of an eye was followed by the regeneration of a truly 

 antennalike appendage. If the antennal regenerate is interpreted as 

 an ancestral reversion, we should have to assume that the primitive 

 crustaceans had three pairs of antennae but no compound eyes, and 

 that eyes were later developed on the first pair of antennae, which 

 then were converted into eye stalks. To accept all this as truth re- 

 quires great faith in imagination. 



