THE CANADIAN ENTOMOLOGIST. 91 



that the wasp was continuing the oviposition. The five produced galls 

 were in November preserved for the experiment of the following year. In 

 the spring of 1875 there were raised from them 35 wasps, all females, and a 

 large number of parasites. These wasps were put again on rose bushes 

 as soon as they appeared on May 26th, June 2nd, 5th, 7th, and oviposition 

 observed on 1 1 twigs. Alter n days some of the eggs were examined, and 

 the embryo found in different stages of development (more details aregiven). 

 Of the 1 r twigs 6 produced galls, out of which were raised in spring, 

 1876, 28 wasps, all females. Those wasps were put on rose bushes June 

 26th, July 2nd, July 4th, and oviposition observed on 13 twigs, which 

 produced 8 galls. Therefore, through three years parthenogenetic-propa- 

 gation was observed. The objection that in experiments thus made in 

 the open air oviposition could have been made on the same twigs by other 

 wasps, can not be refuted directly ; but if it has been noticed so many 

 times that only galls were produced in the observed and marked places, I 

 believe it is allowable to conclude that none except the observed oviposition 

 had been made. 



The other question, if the unimpregnated eggs are regularly devel- 

 oped, was answered in the affirmative by repeated experiments, which are 

 very simple and very easy to be repeated. I put female wasps, raised by 

 myself, which had not been with a male, on shoots of rose put 

 in a jar in water. As soon as the wasps began oviposition, the shoot 

 was placed in a breeding cabinet. After oviposition had ended, the 

 wasp was examined anatomically, and the vesicula seminalis found to be 

 empty. The eggs were examined after 12 hours, and the peripheral 

 layer of cells around the dark yolk was seen ; in the following days the 

 development advanced in the regular manner. 



Dr. Adler gives on five pages more the most interesting details upon 

 the formation and growth of the gall. As Rh. rosae is common here, this 

 part of the memoir is of great Value for American students. If we 

 look in Mr. P. Cameron's paper, we find about this matter on p. 156, as 

 follows : 



" With the bisexual Cynipidae the males are in some species nearly as 

 common as the other sex ; in others, as in Rhoditcs, they are very rare." 

 That is all ! 



On the alternation of generations in Cynipidse the first part of Dr. 

 Adler's memoir contains only (6 pg.) the beginning of the experiments 



