later with an apochromatic objective and condenser, one will 

 be surprised by the accuracy of Baer's observations and the 

 insight of his discussion. 



While his work on the history of development of inver- 

 tebrates was not continued, Baer continued to the end of 

 his life to be interested in the progress of the science 

 of development and responded to every major event in this 

 sphere. 



The discovery, by N. P, Wagner of Kazan, of asexual 

 reproduction in the larvae of diptera from the family 

 Cecidomyidael7 evoked from Baer first a short report 18 and 

 then a long paper. 19 Wagner found that from the ova laid by 

 winged adults come large larvae, which, however, do not 

 pupate. Inside each of these larvae a new generation of 

 larvae develops, feeding on the fat body and other organs 

 of the mother. Inside the larvae of the second generation the 

 third generation originates and so on, resulting in an inter- 

 mediate series of asexually formed generations. The larvae 

 pupate and produce the dioecious winged cecidiums . The 

 discovery of this unusual method of reproduction in dipters 

 caused such great doubt that Siebold did not dare even to 

 publish in the journal which he edited (ZEITSCHRIFT FUR 

 WISSENSCHAFTLICHE ZOOLOGIE ) an article sent to him by 

 Wagner . 



17. N. P. Wagner, SPONTANEOUS REPRODUCTION OF 

 CATERPILLARS AND INSECTS (Kazan, 1862) , 50 pp. 



18. Baer, "Bericht (iber eine neue von Prof. Wagner in 

 Kasan an Dipteren beobachtete abweichende Propagations- 

 form," BULL. ACAD. SC. ST. PETERSB. (1863), 6, 



pp. 239-241. 



19. Baer, "On the discovery by Professor Wagner of the 

 asexual reproduction of larvae, on additional observa- 

 tions on this subject by G. Ganin, and on paedogenesis 

 generally," Appendix to Vol. 10 of ZAPISOK IMP. AKAD 

 NAUK (1866), No. 1, pp. 1-77. 



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