HOW TO GROW GOOD TIMBER. 287 



which would have been formed, had there been no 

 galls, would in their turn have produced branches 

 and leaves. Trees thus infested are crippled as 

 though they had been subjected to constant pruning. 

 As much of the natural history of the cynips, by 

 which these gall-nuts are formed, as is necessary 

 for our purpose, may be gathered from a paper by 

 Mr. Parfitt, who seems to have well studied the gall 

 insect in Devon, its head- quarters. We quote it from 

 the Journal of the Bath and West of England Agri- 

 cultural Society for 1861 : — 



The eggs deposited by the females in the oak buds in September- 

 remain there in a state of apparent quiescence till the following 

 spring ; then, as soon as the sap begins to flow, the irritant injected 

 into the wound at the same time the egg was deposited, or possibly 

 the combined action of the egg and irritant, causes the sap to diverge ; 

 that portion of the bud which should have formed a young shoot is 

 converted into a spherical ball ; the outer scales of the bud fall away, 

 and it is the woody secretion which entirely forms the gall. The 

 cells in the gall are not elongated and regular, as in the young shoot, 

 but confused and irregular ; and in the centre of each gall lies a young 

 grub of the cynips, forming a living nucleus, around which is deposited 

 a thin, hard, woody envelope, much more compact in substance than 

 the sponge-like tissue which fills up the interstice between it and the 

 shining outer coat of the gall. This compactness of structure is a 

 necessary and all-wise provision of nature for protecting the delicate 

 insect which lies within from destruction ; for if the gall were com- 

 posed entirely of large spongy cells, the rapid flow of sap in the early 

 spring would be more than the creature could consume, and it would 

 consequently be drowned. I am aware that some naturalists incline 

 to the opinion that the larvae of the cynips feed on the gall. From 

 this view, however, I venture to dissent ; for not only is it incon- 

 sistent with the structure of the creature's mouth, and the position 

 in which the young larvae, are invariably found, with the head tucked 

 under the apex of the abdomen, but if they fed on the substance or 

 crude material of the gall, the undigested parts would certainly be 



