The Scott is Ji Naturalist. 29 



mature the moment the insect has passed its last transformation : 

 the females are usually disposed to lay the eggs directly, and are, 

 at least many of them, not disturbed by observation ; therefore 

 the experiments with them followed through several years be- 

 come more reliable. 



" The parthenogenesis of Rhodites ivsae was proved by direct 

 raising through three years. The fact is, indeed, more remark- 

 able as males exist in a very small number, about one to a 

 hundred females : but a copulation was never observed. The 

 females carefully separated after their transformation, laid the 

 eggs in confinement. Moreover, a number of females were 

 dissected and showed always the recej^taculum seminis empty, 

 therefore proving that the eggs were not hnpregnated. 



" Other series of observations lead to the interesting discovery 

 of alternating generation by a number of species, which were 

 considered to belong to different genera, but are now proved to 

 be the winter form and the summer form of the same insect. 



^^ Nemvte?'ns fumipennis w^s raised from the galls, the imagines 

 placed 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. fiwiipeiinis was raised. By 

 further growth they proved to be the well-known galls of Spathe- 

 gastcr albipes, which species was raised from them in due time. 

 These two Cynips belong to two different genera, and differ in 

 size. Neuroterus^ the winter form, is agamous, only females 

 known, and the receptaculum seminis was always empty ; the 

 eggs are laid deep in the buds. Spat/iegaster, the summer form, 

 is bisexual, males and females in regular proportion and copu- 

 lating ; 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 confined 

 were raised, and gave in due time Neuroterus. Tlie experiment 

 was made repeatedly on a large scale and with excellent precau- 

 tions, 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 Spathegaster 2iX\Aior Neuroterus to produce 

 the galls out of which they are always raised. Spathegaster pos- 

 sesses 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 per- 

 form 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 



