28o SCIENCE PROGRESS 



of cementing together grains of earth, using the saUvary secre- 

 tion for the purpose, as the honey-bee does for manipulating its 

 wax. With such grains a roughly circular cell is formed upon 

 a wall or fence, stored with honey and pollen, in which the egg 

 is deposited, and sealed up. To this other cells are added, in 

 succession, to the number of eight or ten in all, and although the 

 walls of the cells which are contiguous to each other are smoothly 

 finished, the outer wall is left in a rough condition, so that the 

 effect of the bunch when completed is exactly that of a mere 

 accidental splash of mud. 



Anthophora is another genus of workers in earth and contains 

 some noteworthy species, one of which carries out its work in 

 such a remarkably efficient and economical manner that a 

 detailed description of the procedure, which I was fortunate 

 enough to witness in a Balkan ravine, may be of interest, 

 especially as the species appears to be very local and but little 

 known. 



About the face of a sunny cliff large numbers of these bees 

 were flying. At first sight I took them to be of the ordinary 

 British species, which commonly makes its burrows in old walls 

 and sand-banks, as there were numerous little tunnels into the 

 cliff about three-eighths of an inch in diameter. On looking 

 closer, however, I was astonished to see, sticking out from the 

 cliff face, a number of tubular structures, resembling a small 

 water-tap. Inspection of these tubes showed them to be built 

 up of small grains of earth roughly attached to each other, 

 forming a kind of filigree pattern. Instead of opening direct 

 into the cliff face, the entrance of the burrow was, therefore, at 

 right angles, and, looking directly at the cliff face, it was im- 

 possible to see the opening, while the irregular construction of 

 the tubes caused them to blend very closely with the general 

 surface. 



Bees were very busy entering and leaving the tubes, and 

 numbers were at work on the construction, which was in all 

 stages from a single course round the burrow to complete tubes. 

 Watching one of those which had only a few courses laid, I saw 

 the bee emerge backwards and pass a pellet of earth, glistening 

 with moisture from salivation, to her hind feet, with which she 

 pressed it in position on the wall, where it dried instantly in the 

 hot sun. In a few moments she appeared with another pellet, 

 and so rapidly did she work that, within two or three hours, 

 the tube was projecting over an inch and being gradually 

 curved downwards. I noticed that, while some of the tubes 

 were being lengthened, others were getting shorter, bees being 

 at work taking the walls down and carrying the earth inside. 



The purpose of these tubes seems quite obvious when one 

 knows that these bees are much pestered by a species of parasitic 



