I 



Ari.AX l'Ar.vvKiîis î'kimîis IJl 



Aul. pap. can ])i(»(luc(' «ialls on different s]»e('ies of Papa ver in 

 the open conntry. 



A more convincinj>' experimental proof we obtained tliis year in 

 cnltures. Some years ago we made this experiment in onr garden . 

 but through the kindness witli which the director of tlie Hortus Bo- 

 tanicus in Amstenhim, Prof. lliKfo de Vries, yiehh'd ns some small 

 tields in the garden and excellently assisted by tlie Hortulanus 3Ir. 

 A. J. VAN Lai:i:x, for wliich we wish liere to ex])ress (mr hearthy 

 tlianks to both of tliem, we could ex])osr a number of P a }> a v e r - 

 species to the sting oi' Aid. pap. We used for this Aulaxes which we 

 had collected on the tield in Heilo, so that at tlie tiuu^ at winch the 

 inse(5ts begin t^) Üy we had thousands of animals at our disposal. 

 The different fields iu the garden were i)lanted with se^'eral kinds 

 of 1* a p. i. e. P a j». a r g e m one, g 1 a u c u m , il h ocas t h e 

 8 h i r 1 e y, D a n e b r o g, u m b r o s u m and d u b i u m. We stret- 

 ched large nets of tine gauze over each held , where the Aniuuils 

 had plenty of room, about 1,.')(> M. long, 0,7.") M. broad and 0,50 M. 

 high. Then the aniiiuüs were brought in here thiough an opening 

 and <'very thing remained so for some weeks. The results were sur- 

 prising ; for, tlumgh the insects were seen sitting against the gauze 

 during a fortnight and lived quite well, and though new ones were 

 brought in several tiuies, only the fruits of Pap. d ubi um from 

 lleilo or obtained by buying them, were attacked by .-L^r/c/.r and nime 

 of the other s])ecies , though now all ]>ossibilities of infection were 

 present i. e. the exclosure of P a p. d u b i u m and the great num- 

 ber of tiowers in the state re(piired for the eggs to be laid in them. 



By these proofs it seems convincing, that the Aula.r pup. which 

 occurred in Heilo, produces no galls on other species of T a p a v er 

 and therefore must be a ])hysiological species. 



As we do not kn(>w any spot in Holland wheie the galls on 

 P a p. K h o e a s occur in such a number to iiud^e large exi)eriments 

 with them, we must disi)ose of further investigation , though we do 

 not believe, that they would give uu>re results than these, done with 

 so nuich material in the Amsterdam Hortus. 



Xow let us consider another kind of gall-insect, which has been 

 dc-ri'ibed under one nauu', but occurs on different species of plants. 

 Gtcidomyia rosaria forms the well-known galls on S a 1 i c e s. In our 

 country only those on S. alba and on S. r c [) e n s in the <lunes 



