338 THE ENTOMOLOGIST. 



" Michaelmas daisies," are preserved pure, because ihey are 

 herbaceous : the various portions of a herbaceous plant con- 

 stitute but one individual, whereas every seed originates a 

 new and independent individual. Well, then, if an Eristalis 

 confines its attention to one plant of aster, it only distributes 

 the pollen on that one plant, and the descendants of that 

 plant will resemble the parent, not only in superficial 

 appearance, but also in inheriting the principle of depauper- 

 ation. Nature endeavours to arrest this principle by causing 

 the Eristalis, when loaded with the pollen of one plant, to fly 

 off to a second plant of aster, and distribute its treasure on 

 this second plant, and the pollen which to the flower which 

 produced it was simply a principle of maintenance, when 

 transferred to another flower becomes a principle of reno- 

 vation. My friend Mr. Deane is most kindly assisting me 

 in this enquiry, and I trust, by his assistance, to explain 

 these phenomena more fully hereafter. — Edward Netvnian.] 



Oak Galls. — In allusion to the subject of oak-galls growing 

 in the similitude of acorns, a view which has been repeatedly 

 advocated by the Natural-History Editor of the ' Field,' and 

 ably controverted by Mr. Inchbald in the same paper, the 

 following remarks by Mr. Parfitt are very apposite : — 



" Having paid considerable attention to these galls and 

 their cause, viz., Cynips Kollari, I venture to put a word into 

 the discussion between Mr. Inchbald and yourself. 1 have 

 myself combated the assertion that these galls were produced 

 at the expense of the crop of acorns, for the simple reason 

 that they were, as a rule, produced on the young shoots and 

 bushy growths of the oak, and that the range of the insect 

 was between the ground and ten feet elevation; and the 

 nearer the ground the more numerous were the galls, showing, 

 as I believe, that they require a warmer position than being 

 elevated aloft in the higher trees. And, to bear this out, I 

 have observed that where trees of moderate growth, but too 

 high for the insect to attack when placed on even ground, 

 grew in a hollow or narrow gorge, the insects have attacked 

 these as they had done those of low growth, — a proof, I think, 

 that they require a warmer stratum of air, which the heat 

 radiated from the ground would give, than there is to be 

 obtained at a greater height. Now it is well known to all 

 observers of the oak that it is not these young saplings that 



