88 THE CANADIAN ENTOMOLOGIST. 



made as in mollusks, by vibrating cells, but by the alternate contraction 

 of long spindle-shaped cells, which are attached to the hypodermis. 



Similar experiments with similar results followed also through the 

 whole cycles, proved that Neuroterus lenticular is is the winter form of 

 Spathejdster baccarum. and N numismatis the winter form of Sp. vesica- 

 trix. Dr. Adler adds that experiments with all three species are not very 

 difficult, and he believes that every student will be able to repeat them. 



It seemed to the author more than probable that such alternating 

 generation would not exist alone in Neuroterus. Similar observations and 

 experiments followed through all the cycles proved that Dryophanta 

 scutellaris is the winter form of Trigonaspis erustalis, and Dryophanta 

 longiventris the winter form of Spathegaster Tctschenbergi, but for the last 

 species only half the cycles was till now ascertained. 



Direct observations proved that the egg of Dryophanta is laid with 

 the egg-body downwards and the stem of the egg upwards. The situation 

 is just reversed in Neuroterus, and as the egg is always hatched through 

 the hind portion, the larva of Dryophanta is obliged to make its galls down- 

 wards in the cambium, and the larva of Neuroterus upwards on the 

 leaves. 



Another agamous genus, Aphilothrix, possesses an ovipositor similar 

 to Neuroterus, and it seemed impossible that the large galls out of which 

 it develops could be made by such an ovipositor. Similar observations 

 gave the result that Aphilothrix radicis is the alternating generation of 

 Andricus noduli, and Aphilothrix Sieboldi of Andricus testaceipes. Neither 

 Aphilothrix nor Andricus develop in the same year ; each of those genera 

 needs two years for its development ; therefore the whole cycle runs 

 here through four years, and till now only half the cycle of Andricus bred 

 from Aphilothrix galls has been ascertained by observation. 



I think there can be no doubt that the agamous C. q. aciculata is the 

 winter form of the bisexual C. q. spongifica, just as Neuroterus and Dryo- 

 phanta ; but here both species have the same kind of gall, and both 

 species are less different than those above quoted. 



The remarkable success of Dr. Adler's experiments with the Hymen- 

 opterous galls induced me to compare the rather large collection of Dip- 

 terous galls from Europe and America belonging to the Museum. I found 

 directly some forms entirely similar and corresponding to the alternating 

 galls of Cynips ; but the collection is rather poor in bred specimens of the 



