Mason-Bees. 



477 



days to accomplish. But eight or nine cehs are construe ted, l)nilt oik- against the 

 others, and then the whole of them are coated with a general mass of masonry. 

 When finished she has a dome-shaped structure the size of half an orange. The 

 outer coating of all is composed of grains of sand coarser than those previously used. 

 It harmonizes well with the natural stone to which it is attached ; or on a closer 

 inspection might be regarded as an accidental daub of mud. But the masonry 

 sets so hard that it is with difficulty explored with a knife-blade. 



This building work is carried out in spring, and the solidity of the entire structure 

 has evident relation to the fact that in an exposed position it has to protect the 

 inmates from being dried up by summer's heat, and from being frozen by winter's 

 cold, for it is not until the following spring that the young bees emerge. Then the 

 hardness of the masonry presents no obstacle to them : their jaws are stout enough 

 and sharp enough to pick it to pieces and clear a way large enough to permit of 

 their exit. Yet Fabre found that their powers in 

 this respect were somewhat limited. If the nests 

 were closely surrounded by paper they cut through 

 it as though it were part of their natural enclosure ; 

 but if the paper wall was so arranged that a clear 

 space was left between it and the nest, thev cut 

 through the latter, of course, but did not know how- 

 to deal with the paper as a separate obstacle, and 

 perished in this outer prison. The difference is due, 

 probably, as suggested by Perez, to the fact that 

 in the larger space they do not know where to begin, 

 whilst in the confined space of the cell they are 

 bound to concentrate their efforts upon one spot — 

 that immediately in front of them. 



By marking some of these bees with paint and 

 taking them away to a distance of four kilometres 

 (that is over a quarter of a mile) before releasing 

 them, Fabre found that their homing instinct was 

 so good that they were back working on their 

 unfinished nests next morning, liut though tluir 

 by this means to be very good, he found that when he transposed neighbouring 

 nests they were unable to distinguish their own property, for a bee would 

 unhesitatingly set to work at the substituted nest which now occupied the site of 

 its ()\\ n i)rc\ious labours. If this spot was left blank by the removal of the nest only 

 a slight distance away, the bee returned to the spot and showed great concern, 

 but failed to recognize its nest though it had passed over it in its homeward flight. 



Some of the results of Fabrc's experiments were rather ridiculous, and showed 

 that the bee does not modify its actions according to circumstances as honey-bees 

 do. If he substituted a built and partially provisioned cell for one that had only 

 ju-t been commenced, llic bee would proceed from that point in its operations at 

 which it had left off, and would make the substituted cell much longer than necessary ; 

 yet when it had made the cell a third larger than the normal size it appeared to 



Photo by'. 



[\V. llVst. 



PSOCIDS. 



Outdoor relations of thu book-louse, scarcely 

 known except to the few who make a special 

 study of this small group. They are found 

 upon bark, leaves, decaying wood, etc.. and 

 subsist upon dry refuse. Most of them have 

 two pairs of wings. Those in the photograph 

 are voung individuals whose wings have not 

 vet begun to appear. They are magnified 

 twenty-eiglit times. 



^t>nse of locality was jM'oved 



