444 M. N. Cholodkowsky on the 



biani*), and probably of a large number of Insects whose 

 larvEe are apodous. The ceplialic appendages (antennas and 

 niaxilla3) of the Muscidse are likewise subject to degenera- 

 tion in the larval stage, and subsequently develop a second 

 time. Among the internal organs all parts which in the 

 pupal stage are destroyed by histolysis are also " secondary" 

 in the adult. Similar processes may also be observed among 

 the Crustacea. Thus in the Stomatopoda (in Ericthus 

 according to Glaus) three posterior pairs of thoracic legs do 

 not appear until the end of the liirval stage, while the third 

 to the fifth pairs are developed very early, to subsequently 

 atrophy and then reappear. With reference to this remark- 

 able phenomenon Lang t writes as follows : — " The first start 

 towards the formation of the whole or of the majority of the 

 typical appendages of the Malacostraca, which we here 

 describe and which is subsequently annulled, is without doubt 

 to be ascribed to the power of heredity. The temporary 

 disappearance of a portion of the extremities is most probably 

 a case of adaptation to the special conditions of larval exist- 

 ence, which are so different from those of the adult animal. 

 If, however, in the course of time the first fruitless and useless 

 start became gradually weaker, and were finally entirely 

 omitted, we should in the case of Loricata and Stomatopoda 

 meet with phenomena entirely similar to those in the deve- 

 lopment of the Brachyura, where the formation of the last 

 five thoracic segments and their appendages takes place so 

 extraordinarily late." I would willingly subscribe to these 

 words, and I consider that Lang's conclusions are also to be 

 extended to other animals, such as, for example, the Insects. 

 It is evident that that which is secondary'' in ontogeny is by 

 no means always also phylogenetically secondary. Altogether 

 it appears to me that the conception of what is secondary is 

 only too often misused : should any phenomenon be incon- 

 venient to an author for the working-out of his theories, he 

 simply declares it to be " secondary," and thinks that in so 

 doing he has disposed of the whole question. 



The development of the male gonapophyses has unfortu- 

 nately received much less investigation than that of the 

 oviduct and of the sting. The very interesting '^forcipes " 

 of the humble-bees represent very well developed and even 

 segmented appendages J, which quite convey the impression 



* Balbiani, " Sur I'embiyogenie de la puce," Comptes Reudus Acad. 

 Paris, t. Ixxxi., 1875, pp. 901-904. 



t Lang, ' Lehrbuch der vergleichendeu Anatomie,' Abth. 2 (Jena, 

 1889). 



\ Schmiedeknecht, " Monographic der in Thiiringen vorkommenden 



