Animal Galls. 425 



what the Italian naturalist had reported in so erudite and 

 pleasing a manner. I did not then imagine that it would 

 ever be my lot to speak upon a subject which had been 

 treated with so much care and elegance ; but since I have 

 enjoyed more favourable opportunities than M. Vallisnieri, it 

 was not difficult for me to investigate some of the circum- 

 stances better, and to consider them under a different point 

 of view. It is not, indeed, very wonderful to discover some- 

 thing new in an object, though it has been already carefully 

 inspected with very good eyes, when we sit down to examine 

 it more narrowly, and in a more favourable position ; while 

 it sometimes happens, also, that most indifferent observers 

 have detected what had been previously unnoticed by the 

 most skilful interpreters of nature."* 



From the observations made by Reaumur, he concluded 

 that the mother-fly, above described, deposits her eggs in the 

 flesh of the larger animals, for which purpose she is furnished 

 with an ovipositor of singular mechanism. We have seen 

 that the ovipositors in the gall-flies (Cynips) are rolled up 

 within the body of the insect somewhat like the spring of a 

 watch, so that they can be thrust out to more than double 

 their apparent length. To effect the same purpose, the 

 ovipositor of the ox-fly lengthens, by a series of sliding tubes, 

 precisely like an opera-glass. There are four of these tubes, 

 as may be seen by pressing the belly of the fly till they come 

 into view. Like other ovipositors of this sort, they are com- 

 posed of a horny substance ; but the terminal piece is very 

 different indeed from the same part in the gall-flies, the tree- 

 hoppers (Cicadce), and the ichneumons, being composed of 

 five points, three of which are longer than the other two, and 

 at first sight not unlike a fleur-de-lis, though, upon narrower 

 inspection, they may be discovered to terminate in curved 

 points, somewhat like the claw of a cat. The two shorter 

 pieces are also pointed, but not curved ; and by the union 

 of the five, a tube is composed for the passage of the eggs. 



It would be necessary, Reaumur confesses, to see the fly 

 employ this instrument to understand in what manner it 

 * Reaumur, Mem. iv. 505. 



