3° 
BRITISH GALLS 
bears from two to five sharply pointed spines. Fig. 7 
depicts the young state of the smooth pea gall caused by 
Rhodites eglanteviae. This gall is frequent in August and 
September. It is usually situated on the upper surface of 
a leaflet, occasionally it appears on a sepal or on the stem. 
It becomes brown or reddish towards maturity. Fig. 8 
shows a section of a gall with the larval cavity in the centre, 
and cells of inquilines around it. Fig. 9 is an enlarged view 
of the larva ; Fig. 10 the female insect, magnified. The male 
is very similar, but the abdomen is darker. 
The little Burnet-leaved Rose is frequently attacked by 
Rhodites spinosissima. The galls occur on the stem, leaves, 
petioles, and flower buds. They are green at first, assuming 
a pretty red tint at maturity. Isolated ones are either ovoid 
or reniform ; they frequently occur in conglomerated hard 
woody masses of various shapes. The male of R. spinosissima 
is rare. Cameron figures the female, remarking that he 
had never seen her consort. Many inquilines and parasites 
have been bred from all the Rhodites galls. 
II. GALLS ON THE OAK 
The great point of interest in connexion with many of the 
Cynipidae of the Oak is the alternation of parthenogenetic 
and sexual reproduction. 
Parthenogenesis, as defined by Von Siebold in 1856, is 
the power possessed by certain female animals of producing 
offspring without sexual union with a male. Bonnet, as early 
as 1745, observed the production throughout the summer 
of numerous generations of female yet fertile Aphides. 
Hartig carried out extensive breeding experiments with 
Oak gall-wasps about 1840, and demonstrated the existence 
of numerous species in which only females exist. Bassett, 
in 1873, suspected that the parthenogenetic generation of 
these is followed by a sexual one. Two years later, Dr. Adler, 
who was quite unaware of Bassett’s work and surmises, 
solved the problem by careful experiments with wasps of 
