EGG AND DEVELOPMENT OF THE PHYTOPTUS. 281 



These various stages of the birch wilch-knot P//y/o/?/w.s are 

 figured above, nmiibered respectively 1, 2, 5, and show the 

 egg, the egg slightly altered, and the process of hatching ; two 

 intermediate stages are shown in figures 3, 4. These were 

 from the pubescent Phytoptus galls on the leaves of Viburnum 

 LautfDia (wild guelder-rose), gathered on the 6th of August, 

 at Wootlon-under-Edge, in Gloucestershire, and show in one 

 case (3) the clearness with which running a little turpentine 

 over one of the egg-like bodies at the proper stage of 

 development displays the figure of the gall-mite, and in the 

 other (4) the presence of the striae and the somewhat irregular 

 form which appears to precede hatching. 



In the case of the lime gall-mite 1 found a similar egg 

 amongst Phylopti roaming about beneath the leaf, and also 

 one slightly more obtusely ended in [he Phytoptus gall of the 

 sallow leaf, but not having more advanced specimens to 

 verify their contents by I cannot be absolutely certain of the 

 nature of these eggs. 



Looking at the progression (1 to 5, as figured) from the 

 egg in its perfect form through the very gradual steps to the 

 exclusion of the gall-mite, it appears to point to the smooth, 

 obtuse, oval body being the true Phytoptus egg, and that the 

 Phytoptus is excluded from it, as far as external form goes, 

 in perfect development. 1 have never seen the gall-mite free 

 itself entirely from the egg pellicle ; but whether in the 

 smallest size, corresponding with those of which only a 

 portion showed projecting from the egg, or in the largest 

 growth, 1 have not met with any variation of characteristics 

 beyond colour and slight difi'erences of figure. In autumn, 

 as far as examination goes of the lime tree and common 

 maple infested by Pliytopti, the mite may frequently be 

 found straying on the under side of the leaf, on the twig, and 

 also sheltering in the crannies at the base of ihe leaf-bud, 

 rather than in the galls; the mite-galls appearing sometimes 

 entirely em])ty, sometimes inhabited. 



On the maple leaf the galls vary much in size and shape, 

 from the common irregularly-formed clustered and reddish 

 galls of the upper side of the ]eal' {Cephaloneon myriadeum, 

 Brcmi), to the larger solitary kind in the axils of the veins, 

 ])()ssibly the Cephaloneon solitarum ; but in the specimens 

 belbre me the steps from one form of gall to the other are so 



2p 



