THE CANADIAN ENTOMOLOGIST, 87 



on oak buds, the oviposition observed, and the plants isolated. The galls 

 originating from them were entirely different from those galls out of which 

 N. fumipainis was raised. By further growth they proved to be the well 

 known galls of Spathegaster albipes, which species was raised from them in 

 due time. These two Cynips belong to two different genera, and differ in 

 size ; Ncuroterus, the winter form, is agamous, only females known, and 

 the receptaculum seminis was always empty ; the eggs are laid deep in 

 the buds. Spathegaster, the summer form, is bisexual, males and females 

 in regular proportion and copulating ; the receptaculum seminis of the 

 egg-laying females being always filled with spermatozoa. The eggs are laid 

 on the leaves. To complete the cycles, Spathegaster galls carefully con- 

 fined were raised and gave in due time Neurotcrus. The experiment was 

 made repeatedly on a large scale and with excellent precautions, so that 

 no doubt is possible. Now as the fact is known, it is rather remarkable 

 that it was not sooner discovered, as it is entirely impossible for Spathe- 

 gaster and for Neuroterus to produce the galls out of which they are always 

 raised. Spathegaster possesses a short and somewhat degraded ovipositor, 

 just fit to injure the superficies of a leaf and to lay the egg ; Neuroterus 

 possesses a long, bent and complicated ovipositor, able to perform the 

 rather difficult act of entering the bud and laying the eggs in the basis of 

 the bud, but would be scarcely able to injure the superficies of a leaf in 

 the same manner as Spathegaster. I think this admirable discovery is 

 of the greatest importance for further observations. If we find again a 

 species with an ovipositor not fit to make the galls of the species, we are 

 justified in presuming a similar alternating generation with some other 

 species. 



The difficult question how the eggs of Cynips are able to pass through 

 the comparatively small ovipositor is described with much detail and 

 acumen. The observation was only possible by the ingenious device 

 of chloroforming the insects in the act of oviposition, and making 

 an anatomical investigation of the" parts. By repeating the obser- 

 vation many times in different stages of the act, a full series of observa- 

 tions, one completing the other, gave a clear and satisfactory result, and at 

 the same time the place was ascertained in which the egg was laid. A 

 large number of other interesting details concerning the formation, struc- 

 ture and the growth of the galls, are given, which must be studied in the 

 original paper. I may only add the surprising fact of the continuous 

 rotation of the embryo in the egg, till it is hatched. The rotation is not 



