142 » J. Rf.i.txvaax — DocTF.rts v. Lf.etwkx 



are frequent. The ^alls outwardly differ much ; esiiecially by the sil- 

 very white and sliinin,i>' liairs of tlie r e p e n s-<>all, which are also no- 

 tably iiiucli smaller. I>y <-ulti\ atin^- l»otli it a])]»care(l. tliat the a 1 b a- 

 galls came out al>out 2 weeks earlier, thoujiii they were collected in 

 eachother's neighbourhood ; the li'iiats were not different outwardly. 

 We put both on several !S a 1 i \ - soits. Each soon laid ejfgs on the 

 Sali X, wliere it cauie fnun. (Jecidomii'ta rosaria from tS a 1 i x alb a, 

 wlii(;h we had in «iieat number, Hew round l)ranches of S. re]) e n s, 

 a u r i t a and p u r p u r e a used for tlie researches, l)ut m^ver as far 

 as we could see, ]>ut one e.ii_i> on tliem. l»nt ]»laced tliem often on 

 the glass of the box . wliere tliey were ke])t in and in which the 

 plants stood. Also m> <>alls at all were formed afterwards. 



From the investi<iations of Iîe^KKIXCK (1) it l)e<'ame known . 

 that Kematus (lidlicohi from Salix alba was iiever made to 

 lay eji'ji's on Sali x a m y <i d a 1 i n a and s<> it is very ju'obable, 

 that also of these <iallwas]>s there lixcs a special sort of Xematua 

 on each sort of Salix, on wliicli ^alls are forim^d. 



The same we were able to o])serve of Pcrrinid Vfronicac. cominji" 

 from ii>alls on V e r o n i c a (' h a m a e d r y ■?;. In captivity these 

 laid egjis diicctly on V er. Ch a m. and ualls weie forme('. but on 

 V e r. o f f i (• i n a 1 i s on which Fer. rcronicde occurs also, no e<ij;s 

 were laid down. AAso Pmisin'' s from galls on ^' e r. of fi <•. could 

 not be made to i)ut their eggs on V r r. (' li a m a e d r y s. 



We could extend these examples with another nuuiber of expe- 

 riments whi<'h we made, but shall only name a negative result obtai- 

 ned with eggs of ì>yì/<>j)hi(iif(( foìii. The animals were o]>ened and 

 the eggs taken out in a ]»liysio]ogical salt-solution. Then a hole was 

 made in an oak-bud and the eggs carefully brought in and put on 

 the youngest leaxes and the growing point. The woujid afterwards 

 was carefully shut with grafting-wax <n- oiled ]»a]>er. Though we trea- 

 ted a number of buds in our garden in this manner and tii-st made 

 experiments on oaks in the Hortus liotanicus with buds , wounded 

 in the same manner, save the jHitting in of eggs, the results of both 

 experiments were alike and the young branches only showed changes 



(1) M. W. Beykrixck — Ueber das C'ccidium vou Xeuiatus capreae auf Salix 

 amygdalina. Bot. Ztntuug. 1888. N. 1 uud 2. 



