April, 1904.] Galls and Insects Producing Them. 123 



opened the egg can still be seen lying within the cavity. The 

 embryonic development is as yet unfinished and three weeks 

 elapse before the larva emerges from the egg to find around it the 

 material prepared for its nutriment. In this case the wound 

 caused by the fl}- is the immediate exciting cause of cell activity, 

 and leads to gall formation." 



M. W. Beyerinck, in a paper regarding the growth of the gall 

 of Nematus caprea on Salix amygdalina holds a similar view. I 

 have not seen this paper, but an abstract^i^ of it says: "The 

 production of the gall is undoubtedly due to the matter secreted 

 by the poison gland, which is, consequently, homologous with 

 the poison of Hymenoptera aculeata ; when the insect does not 

 deposit an egg in the wound which it makes, the quantity of 

 albuminous matter poured into the vesicle is always less than 

 when an egg is deposited ; by careful observation it is possible to 

 assure oneself that the size of the gall is always proportional to 

 the size of the wound and the quantit}^ of albuminoid matter 

 introduced. By an experiment in which a deposited egg was 

 punctured by a fine needle, it was shown that the gall is due to 

 the parent and not to the egg ; but, of course, in such a case the 

 gall remains small ; neither the egg nor the larva are necessary 

 for its production, though their presence exercises a certain influ- 

 ence on the regularity of their development." 



The ovipositors of the Cynipidae vary in length and in the 

 amount of coiling within the abdomen. All present the same 

 general characters. So far I have been unable to detect any 

 relationship between the length and character of the ovipositors 

 and the location and complexity of the galls (Figs. 94 to 98). 

 Adler claims that the egg is always deposited in or near the 

 Cambium layer of the plant. I am inclined to accept this state- 

 ment, but have made no special effort to verify it. If Adler' s 

 observations are correct the length of the ovipositor would be 

 associated not with the depth of the Cambium from the surface 

 of that part of the mature plant affected, but with the location 

 of the Cambium at the time of oviposition and with the difficul- 

 ties which the insect would experience in forcing the ovipositor 

 to the desired point. 



Oviposition usually occurs before the buds are open, and the 

 eggs may be placed in three positions ( i ) in the stem, as in the 

 case of Rhodites radicum O. S., R. globulus Beut., Andricus 

 cornigerous O. S. ; (2) in the apex of the incipient stem as in 

 Andricus clavula Bassett, and Holcaspis globulus F'itch ; or (3) 

 in the leaves of the bud as in Rhodites bicolor Harris, Amphi- 

 bolips confluentus Harris, A. inanis O. S., A. ilicifoliae Bassett, 

 Neuroterus irregularis O. S., A. seminator, Callirhytis tumifica 



••■Jour. Roy. Micr. Soc, 1SS7, p. 746. 



