THE NUMERICAL ASPECT OF OAK GALLS. 23 



Nmroterus fiiiniimiinu — 



3453 galls on 15 leaves off one Imsli. 

 Fewest galls on one leaf . ,115 



Most „ „ „ „ . . 489 



Average per leaf . . .230 



AYeight of the galls, 2 dr., 1 sc, (3 gr. 

 yeuroteras leiitlcularis — 



1944 galls on 12 leaves off one bush. 

 Fewest galls on one leaf . .72 



Most ' „ „ „ „ . . 288 



Average per leaf . . .162 



Weight of the galls, 4 dr., 1 sc, 17 gr. 

 These leaves were gathered after twenty-two days 

 without rain. The galls were removed from the 

 leaves, counted, and weighed at once, all the figures 

 being verified in several ways. 



To ascertain if the galls of N. famipennis ^\ow\ii\\?iYQ 

 weighed more had the weather been wet, they were 

 spread in a shallow dish and exposed to rain for three 

 hours. The}^ were then allowed to dry off superfluous 

 moisture. Upon weighiug again it was found they 

 were 12 grains heavier than before. 



So far as the author's o1)servations have extended, 

 the largest number of galls of a few other species on 

 single leaves are : 



in diameter. 



Trifionaspis crustalis . 12 within an area 15 cm. 



in diameter. 

 On one leaf, 14 x 9 cm., there were growing: 



1 Xeiiroterus of^treiia . 2 Dryopltanta scntellaris. 



