The Sizes, Shapes, and Colours of Galls 1 1 



stalk, or arranged along it in a moniliform manner. Several 

 are cigar or torpedo shape, or lemon shape ; others are pyriform, 

 bursiform, hemispherical, sessile, or pedunculated. Two at least 

 are rosette in form ; and although one, Cecidomyia craUegi, is 

 exceedingly common, it commands as much admiration as does 

 C. rosaria, which is far less plentiful. A few conical forms 

 appear usually on the leaves. Others are pyramidal, spindle 

 shape, or ovid, and several are pineal in form. One at least 

 {Monochetus sulcatus) is cymbiform. The remainder are ir- 

 regular in outline, being constricted, curved, or dwarfed during 

 growth. The galls formed by Rliodites nervosus have sharp- 

 pointed spines or thorns on the surface, and in this respect they 

 are unique. 



The colours are not so numerous as the shapes. Many 

 galls have most delicate and exquisite shades of colour when 

 nearing maturity of growth. 



The predominant colour is green, very delicate shades of 

 which may be seen at various stages in the growth of the galls ; 

 in fact, as may be supposed from the positions occupied, they 

 are all more or less green, changing only as they approach or 

 attain maturity. Some galls are of very sombre hues, un- 

 relieved by any colour at all ; others have no definite colour, 

 other than green ; a large number, however, are very bright 

 and attractive. 



Greens of every shade, from a very pale yellowish to a rich 

 olive, are common. Yellows, from a very pale tint passing 

 through all shades until a deep orange is reached, are not 

 so numerous. Reds, from a faint pink blush to a purple or 

 reddish brown which quickly passes into a chocolate-brown 

 are less plentiful. Many galls at first are suffused with pink, 

 which, as growth proceeds, deepens to red, then to purple 

 or reddish brown, and finally chocolate-brown or black. One 

 kind only is silvery white, and remains so until maturity is 

 past. It is caused by the larva of Hcdya accriana on twigs 

 of Populus alba. The gall caused by the larva of Eurytoma 

 hyalipennis is remarkable in gradually losing its colour as 

 growth proceeds. At first the young leaves are striped 

 with pink ; this gradually becomes paler, until ultimately the 

 entire gall is an ordinary straw colour. Very few are like 

 Cecidomyia pteridis, which, beginning as a very pale green, 



