TJie Scottish Naturalist, 35 



to be empty. The receptaculum is in the agamoiis species 

 always somewhat atrophied ; in the bisexual species the external 

 membrane is pigmented, and even if empty, forms a ball. 



" Besides those experiments, others were made at the same 

 time in the open air. The oviposition was observed March 31st 

 on 5 buds, April ist on 7 buds, April 2d on 12 buds, April 7th 

 on 12 buds, April loth on 40 buds, April 12th on 38 buds; al- 

 together on 114 buds. A curious fact is related, that in 42 buds 

 the ovipositor of the wasp Avas found left in the bud. 



" The results of the different experiments were as follows : 

 The small oak-tree in the tub was kept in the room, and began 

 to bud in the beginning of May, and the leaves were developed 

 enough. May 14th, to see if galls were forming. Of the 36 marked 

 buds, 13 had no galls produced; on the others, in all 36 galls 

 were counted. It is to be remembered that here oviposition was 

 made and observed in the room, the twigs carefully isolated by 

 glass tubes, and kept in the room till the tree began to bud. 

 Therefore it is impossible that eggs could have been laid by other 

 wasps. The galls were those of Spath. albipes. Concerning the 

 experiments in the open air, the leaves of the tree were. May 

 20th, so far developed that the formation of galls could be ob- 

 served, and again the galls were those of Spath. albipes. Out of 

 the 144 buds marked, galls were found on 6d>, with about 300 

 galls. The oak chosen was a small shrub four to five feet high, 

 easy to be examined, and showed nowhere any other galls. 



" Out of the collected galls a large number of Spath. albipes was 

 raised in the first half of June, and were put in a breeding cabinet 

 with a small oak-tree. As no copulation nor oviposition was 

 observed, Dr Adler decided to try observation in the open air. 

 He succeeded, June 3d, in finding several females of Spath. 

 albipes in the act of oviposition, and secured six wasps, several 

 leaves, and marked four leaves on which he had observed ovi- 

 position with a thread. The lens showed that an egg was de- 

 posited. The secured wasps were put on the small oak in the" 

 breeding cabinet, and now the wasps were observed ovipositing 

 on two leaves. The next day the wasps were examined, and 

 showed the receptaculum seminis full of spermatozoa. On June 

 5th and 6th several more wasps in the act of oviposition were 

 observed, and six leaves marked. In the first fortnight no 

 change in the leaves was seen ; in the third week the substance 

 of the leaf where the egg was deposited was visibly thickened — 

 the larva had left the egg, and the formation of the gall began. 



