46 ENTOMOLOGICAL NEWS [Jan., '15 



The development of insects early interested him, and the 

 Abhandlungen of the Senckenberg Society of his native town 

 for 1862-63 contains one of his first papers on this subject: 

 die Entstehung des vollendeten Insektes in der Larve und 

 Fuppe. A paper on the embryology of various insects ap- 

 peared in 1864 in the Archiv filr Anatomic und Physiologic. 

 The Zcitschrift filr Wisscnschaftlichc Zoologic for 1863 and 

 1864 contained those two great memoirs, Die Bntwicklung der 

 Diptcrcn im Bi and Die nachembryonalc Entzmcklung der 

 Musciden, results of nearly four years' work. The first of 

 these dealt with the embryonic development of Chironomus, 

 Musca vomitoria and Pulex canis. 



From the second [Weismann wrote at the time] one will see how. 

 in a very unexpected manner, the head and thorax of the fly together 

 with their appendages are already formed in the larva, nay in the em- 

 bryo, how they arise in the interior of the body cavity separated from 

 each other and, after pupation, grow together into the parts of the 



fly's body But not only the walls of the body in the 



family of the Muscidae exhibit such a peculiar history but also the 

 internal organs are reformed anew in a surprising manner out of the 

 entirely destroyed larval body. 



It was in this memoir that the term "imaginal disks" (Imag- 

 inalscheiben) was first applied to those minute parts present 

 in the larva from which the imaginal, head, thorax and append- 

 ages are formed. In 1866 appeared, in the same Zcitschrift, 

 Die Metamorphose der Corcthra plumicornis, in which its con- 

 tinuous development was contrasted with the discontinuous 

 type represented by Musca. In the Festschrift for his teacher 

 Henle, in 1882, were his Bcitrdge zur Kenntniss der ersten Bnt- 

 ztncklungsvorgange im Insectcnci. 



Another entomological topic to which Weismann directed his 

 attention was the seasonal dimorphism of the Lepidoptera, not 

 merely to solve that particular problem but also to take, as he 

 hoped, a step forward in the question of the transformation of 

 species. A paper of 94 pages on this subject in the Annali of 

 the Genoa Museum for 1874 appeared also as the first of his 

 Studien sur Dcsccnden:;-Thcorie (Leipzig 1875). 



The second (1876) of these Studien dealt with the origin of 



