OF WASHINGTON. 145 



The first paper of the evening, an abstract of which fol 

 lows, was by Doctor Howard : 



POLYEMBRYONY AND THE FIXATION OF SEX. 

 By L. O. HOWARD. 

 (Author's Abstract.) 



The speaker described his early observations on strange 

 methods of pupation among the Chalcididse (American Nat 

 uralist, 1882 ; Insect Life, Vol. IV, 1891 ; and Proceedings of 

 the U. S. National Museum, 1892), indicating the existence 

 of certain unexplained phenomena in the development of cer 

 tain hymenopterous parasites of the family Chalcididse, which 

 have subsequently been cleared up by the discovery of Marchal 

 of the existence of the extraordinary process known as poly- 

 embryony, by virtue of which from a single egg there may 

 come very many adult individuals. He reviewed the work of 

 Bugnion on the anatomy and habits of Encyrtus fuscicollis 

 (1891), a note by Giard (1898), and several papers by Paul 

 Marchal culminating in his startling work entitled Researches 

 upon the Biology and the Development of Parasitic Hymen- 

 optera Specific Polyembryony or Germinogony (1904). He 

 further reviewed a paper by F. Silvestri entitled Contributions 

 to the Biological Knowledge of Parasitic Hymenoptera: (i) 

 Biology of Litomastix truncatellus (1906) ; and the admirable 

 summary of Marchal's work by Bugnion, also published in 

 1906. The paper in full up to this point is published in 

 Science* 



The speaker then called especial attention to the extreme 

 interest attaching to further observations of this wonderful 

 life process, and dwelled upon the abundance of material for 

 study existing on every hand, the requirements for its inves 

 tigation, now that the initial discoveries have been made, being 

 simply good laboratory facilities and a skilled technique to 

 gether with trained powers of observation. These are to be 

 found with many institutions and many individuals in this 

 country, and there is every hope that before long the darkness 

 that has existed in our knowledge of the intimate early life 

 history of the parasitic Hymenoptera will be changed into the 

 bright light of accurate knowledge. 



The speaker exhibited a large series of species of the encyr- 

 tid genera Copidosoma, Litomastix, and Ageniaspis, together 



a Science, n. s., Vol. XXIV, No. 625, December 21, 1906, pp. 810-818. 



