Apkil 26, 1895.] 



SCIENCE. 



461 



that this complex procechire slioukl be re- 

 peated so often \\-ith such great accuracy, 

 and proceeds to describe the tactile hairs 

 connected with the o\'ipositor which permit 

 the fly to carry out the operation. He further 

 states that, while oviposition in the surface 

 of leaves is in its nature easier, the mech- 

 anism of oviposition is exactly the same as 

 in buds. 



We thus have two diametrically opposed 

 views as to how the CjTiipid egg passes 

 dowTi the ovipositor, the oviduct or passage 

 of which is but one-fourth as wide as the 

 egg-bodj' itself, and into the puncture pre- 

 pared for it. Hartig gave a perfectly sim- 

 ple explanation, and one generally accepted. 

 While it is difficult to understand how the 

 egg can be pushed into the puncture with 

 the swollen egg-body entering first, yet Ad- 

 ler goes into elaborate details and is so care- 

 ful that one is scarcely justified in question- 

 ing his conclusions. There is, however, 

 good reason for doubting their accuracy as 

 applied to all sjiecies and for believing that 

 the method described \>y Hartig does also 

 obtain and that there are even further modi- 

 fications of the process. 



In controverting Hartig and referring to 

 his figures of eggs and ovipositors, Adler 

 gives no indication whether the eggs were 

 taken from the buds after being deposited, 

 or from the ovaries or from the ovipositor, 

 and my own experience with these and 

 other ductile and extensile eggs with long 

 egg-stalks would indicate a very varjing 

 length of stalk according to these varying 

 circumstances. Again, he evadently has 

 misjudged Hartig in assuming that the lat- 

 ter describes the passing of the egg down 

 the minute channel of the seta, for Hartig's 

 figures, as well as his description, make it 

 clear that he had in mind the actual facts, 

 viz., the passage of the egg down the channel 

 formed bj' the connection of the two spi- 

 cuhe with the seta. He is quite clear on 

 this point and refers to the seta as the egg- 



guide (Eileiter) and not as the oviduct. 

 He also elaborately describes and figures 

 the eggs in the ovaries, with the swollen 

 egg-body away from and the stalk directed 

 to the base of the ovipositor. 



Mj^ own studies of the oviposition of Cal- 

 Urhytis clamda O. S. in the buds of Quereus 

 alba in April show that the eggs are in- 

 serted by the egg-stalk into the substance 

 of the leaf, and that the fluids are first 

 gathered in the posterior end which is not 

 inserted. The fluids are then gradually 

 absorbed from this exposed portion into the 

 inserted portion of the egg and by the time 

 the young leaves have formed the exposed 

 shells are empty, the thread-like stalk has 

 disappeared and the egg-contents are all 

 contained within the leaf tissue. The larva 

 now hatches and young galls rapidly form, 

 the colorless and shriveled egg-shell being 

 still often exposed in position and generally 

 some distance from the position of the larva, 

 a difierence doubtless representing the orig- 

 inal length of the inserted egg-stalk.* 



These observations certainly comport 

 more with the conclusions of Hartig than of 

 Adler, though they indicate a quite difierent 



* This agamic Rail-fly produces a hemispherical 

 gall Involving both sides of the leaf, the cells in the 

 center being connected by loose spongy fiber, and 

 from it comes the se.xual species, Callirhi/li-i fuiilis O. 

 S. Tliis in turn produces the twig gall from -which 

 the agamic C. q-clnniln is derived. >Ir. H. F. Bas- 

 sett (Psi/clie, Vol. 5, pp. 235-8, December, 1889) 

 has connected Qillirkylis fulilia O. S. with a new spe- 

 cies which he there describes as Callirhi/lw radieis, 

 reared from a gall which is, practically, a blister-like 

 swelling of the root. Tliere is here either an error as 

 to determination or else we have another interesting 

 discovery in connection with these insects, viz., that 

 the same species may indifferently produce a gall on 

 the root or on the twig. Wlien we remember how 

 readily nature in many cases will convert a root into 

 a twig, and rice vena this last explanation will not ap- 

 pear so improbable. I may add that Mr. Ashmead, 

 who lias reared the fly from the clmiila gall, has care- 

 fully corajjared it with those actually ol)ser\-ed ovi- 

 positing in the buds and agrees with me that they 

 are identical. 



