286 Dr. H. Adler’s Researches on 
and broader, and the antenne longer than the Spathegaster 
form. The differences which are perceived in the abdomen 
are due to the structure and form of the ovipositor, which 
vary according to the duty it is called upon to perform and 
the part which it is destined to pierce. 
The reproductive organs seem to have on the whole the 
same structure in the females of the two generations. In 
both the ovaries are formed of a great number of ovarian tubes, 
in each of which are found from six to twelve eggs. Gene- 
rally the agamic generations have a greater number of 
ovarian tubes, and there. are more eggs in each tube. One 
gland, which M. Adler regards as playing the part of a pros- 
tate, although more developed in the females of the sexual 
generation, exists also, however, in those of the agamic 
generation. What is still more remarkable is that the seminal 
receptacle is found not only in the females of the agamic 
generations which alternate with the sexual generations, but 
also in those of the species which propagate only by partheno- 
genesis. A certain degree of atrophy of this organ is found, 
however, among the agamic females in comparison with 
that among sexual females. The persistence of the seminal 
receptacle in these parthenogenetic insects plainly shows, as 
M. Adler remarks, that at a very remote period males must 
have existed. Other facts described by the author tell the 
same tale. There is found, moreover, among the Cynipide 
(Rhodttes rose and &. eglanterie) living on other plants than 
the oak a manifestation of atavism, thus confirming the bonds 
which exist between the sexual and agamic states. Al- 
though reproduction among them has become entirely par- 
thenogenetic, yet at times males appear, although probably 
no copulation has taken place for a long period. 
Besides the differences existing between the perfect insects, 
the two alternating generations are distinguished also by the 
longer or shorter time necessary for the development of the 
ege and of the larva, and by the division of the phases of 
this development. ‘The larve of Newroterus and those of 
Spathegaster also exhibit differences m the form of their man- 
dibles, these organs being adapted to the kind of life of each. 
The researches of M. Adler have not been merely limited 
to the Cynipide of the oak. Other Hymenoptera, parasitic 
on animals and plants, have disclosed to him some interesting 
facts, which show to what a great extent parthenogenesis 
prevails among the insects of this order, and under what 
different conditions it shows itself in the various groups, and 
even in the species of the same genus. 
Von Siebold proved that in Nematus ventricosus the males 
