QUEKETT MICROSCOPICAL CLUB. 341 



theoretical considerations. The reason for this peculiarity has not 

 been discovered. 



The Hon Secretary then read a note by Mr. H. Wood on 

 " A New Polariser of Large Field." The polariser, which was 

 exhibited and described, was the result of the development by Mr. 

 Wood of a suggestion of Mr. Nelson's. The apparatus consists of 

 a tube 4 in. long, having at each end a plano-convex lens, convex 

 side outwards, of l^ in. diameter and 2 in. focal length. (Mr. 

 Nelson suggests using the lenses from an old binocular.) A ^-in. 

 nicol is fixed in the middle of the tube, and at each end of the 

 nicol is a diaphragm as large as its aperture will allow. Between 

 each diaphragm and the plano-convex lens at the corresponding 

 end of the tube is placed (near to the diaphragm) a double concave 

 lens. The light from the lamp is parallelised and then passes 

 through the polariser, wliich can be rotated, to the mirror. The 

 effect of the lens is to send the light through the nicol in a direction 

 parallel to its axis. The polariser was exhibited, yielding a field 

 equal to the back lens of a full-sized Abbe condenser. 



Mr. F. Addey was then called upon to give his lecture on " Pinus 

 sylvestris." A few years ago Mr. Addey had spent a summer 

 working at P. sylvestris (the Scotch fir), and he proposed to 

 describe its structure and method of reproduction so far as he had 

 seen it, illustrating his lecture by the photographs he had taken 

 of the tree and of the sections he had made of various parts of it. 

 If the end of a branch of P. sylvestris be examined in autumn it 

 will be found that there is a large terminal, resin- covered bud, 

 surrounded by several other large resinous buds, in between the 

 scale leaves with which the end of the branch is covered. Lower 

 down the long shoot which terminates the branch are numerous 

 short shoots, each bearing two acicular foliage leaves. In the 

 spring the terminal bud lengthens, forming another long shoot, 

 and the lateral buds form a whorl of long shoots. Each year this 

 process is repeated, the distance between one whorl of branches 

 and the next roughly representing one year's growth. The result 

 of this method of growth is a long straight stem with lateral 

 branches, the outline of the tree being pjTamidal. The leaves 

 persist for only two years, and the lower branches soon begin to 

 drop off, so that the tree loses its symmetry. A series of photo- 

 graphs of sections of the stem was then shown, and the structure 

 explained. If a transverse section of a young elongated shoot be 



