CH. XVn.] VARIOUS SPECIES OF SAWFLIES. 249 



positor engaged in the branch ; a moment after, she 

 draws away quickly the largest part of it, and emits 

 at the same time a frothy hquid, which rises as far 

 as the external edges of the notch, and sometimes 

 beyond them. Some authors have thought that the 

 use of this liquid was to bedew and moisten the 

 eggs, but Valisnieri believes that it serves to pre- 

 vent the aperture from closing. Be this as it may, 

 after the female has emitted this fluid, she with- 

 draws her ovipositor, and proceeds to the fabrication 

 of another hole. Sometimes she makes but four in 

 a line, one after another; most frequently, how- 

 ever, she makes about a score. The part of the 

 branch which is notched in so many places presents 

 nothing remarkable the first day of the operation, 

 and it is not until the following day that it begins 

 to assume a brown colour ; and in the sequel all 

 the wounds become raised, and acquire more and 

 more convexity every day. This growth is owing 

 to the augmented volume of each egg, as it daily 

 grows larger. It forces the skin of the branch up- 

 wards, and the aperture to grow larger. This last 

 finally becomes considerable enough to give passage 

 to the larva, which, in coming out of the egg, quits 

 its retreat to seek the leaves of the shrub on which 

 it is nourished." 



The singular fact of the increase in size of the 

 eggs after deposition, and previous to the bursting 

 forth of the young, is quite at variance with the ordi- 

 nary circumstance that the eggs of oviparous animals 

 attain their full size previous to their being deposit- 

 ed. An analogous case, however, exists, not only 

 among the gallflies and ants, but also in the eggs 

 of fishes, whose size in hke manner is said to in- 

 crease previous to the exclusion of the young. 

 Reaumur considered that it was in consequence 

 of imbibing nutriment in some unknown manner 

 through the membranous covering from the vege- 

 table juices which surround them ; the eggs at their 



