90 THE CANADIAN ENTOMOLOGIST. 



forms, and observations made by myself on one species in the last year 

 seem to favor his opinion. 



Such alternations stated without doubt for Hymenoptera and some 

 Hemiptera, and probable by analogy for some Diptera, will certainly not 

 fail to occur in other orders, and are probable in some Lepidoptera 

 heterocera. 



A paper by Mr. P. Cameron, in the Scottish Naturalist for April, 

 1878, the substance of which is incorporated and fully approved in the 

 President's Address to the Entomological Society of London, arrives at 

 conclusions entirely unfavorable to Dr. Adler's memoir. To corroborate 

 my views about the memoir I wish to give a few statements. 



Dr. Adler gives the facts upon the discovery " of the Parthenogenesis 

 of Rhodites rosac " on ten pages, about two-thirds of the first part of his 

 memoir. 



In May, 1872, Rh. rosac in large numbers was observed ; some few 

 males appeared, which were put, together with several females, in the 

 breeding cabinet; but no copulation was observed. For further experiment 

 were chosen females appearing later, of which, by careful observation, it 

 was certain that none of them had been with any male. Those 

 females were put on bushes of Rosa canina on May 10th — 12 wasps, May 

 13th — 16 wasps, May 26th — 10 wasps, June 2nd — 6 wasps; together, 44 

 wasps. Of those 26 wasps were observed in the act of oviposition, and 

 the twigs were marked with a thread around each. The first formation 

 of a gall was observed June 5th, and in all only nine twigs formed galls ; 

 giving the positive result that unimpregnated eggs had developed. The 

 experiment was tried again for the purpose of having surer results by repe- 

 tition and to investigate why the first experiment was without result in so 

 many cases. In 1874 there were put, June 22nd, on rose bushes 8 wasps, 4 

 of which were observed in oviposition, none producing galls ; June 23rd, 

 of 10 wasps, 4 observed in oviposition, 2 producing galls ; June 27th, of 

 12 wasps, 5 were observed in oviposition, producing 3 galls. 



Of the 13 wasps observed in the act of oviposition, 4 were dissected, 

 and the receptaculum seminis stated to be entirely empty (without sper- 

 matozoa). Every one of the wasps spoken of was carefully observed and 

 not lost sight of till the wasp had begun the oviposition, in which act 

 some persevered for more than 24 hours. Of course observation was not 

 followed through this whole time, but every few hours it was again observed 



