615 



has the pubescent zone imbued with the viscous fluid, abounding with 

 active molecules, and easily diffusible in water ; or it may consist 

 only of the reflexed orange border underneath. The latter is i;pn- 

 dered highly probable by the fact that pollen grains are constantly 

 found attached to this part with their tubes fully developed, and some 

 of them in positions scarcely accessible were it not for the curved 

 form of the filaments, which give a favourable direction to the pollen 

 as it falls from the anther. The central tissue, from this part to the 

 base of the style, is composed of very slightly cohering oblong cells, 

 of the same orange colour ; and the whole may be compared to a 

 funnel with a long narrow stalk, lying betvreen two bundles of vascu- 

 lar tissue, which perforate the expanded part of the funnel on two 

 opposite sides, and then pass up into the region above the true stigma, 

 where they become greatly expanded and multiplied, so as to form a 

 cylindrical congeries of spiral vessels, whose dark colour might lead 

 to the supposition that they contained air, if it were not that there is 

 no appearance of extricated bubbles on pressing portions of them 

 when immersed in water. A portion of the placenta has the same 

 orange tint, and is probably a continuation of the stigmatic tissue ; 

 but I sought in vain for pollen tubes in this region, and indeed they 

 were not visible in the style, where they would have been so conspi- 

 cuous had they been present. It may be that fecundation in this 

 plant is of rare occun-ence. — Id. 



309. On the glandular ivoody tissue of Conifer (b. The structure of 

 the circular glands being still a subject of debate among physiologists, 

 permit me to send you a drawing of a longitudinal section of pine 

 wood, perpendicular to the medullary rays, exhibiting sections of the 

 glands. By way of explanation, let the contiguous walls of two 

 cells, otherwise in perfect contact, be supposed 

 to be separated here and there by small lens- 

 shaped blisters, which are perforated in the 

 middle, and the cavity filled up with a yellow- 

 ish nucleus, having a slight depression in the 



centre of each convex face, immediately be- section^ Fir w^7(Dean! 

 low the aperture of the membrane. The draw- ^''Z'^^^i^^^.T^^Zl 

 ing represents the object magnified 300 diameters. — Id. 



310. On the spiral porous cells in the wood of the Yew tree. The 

 representation of these, after Kieser, in Lindley's Introduction, ed. 2, 

 does not agree with my own observations. The spirally lined woody 

 cells I believe to be perfectly distinct from the small oblique glands 

 which are .supposed to be situated between the spires, and 1 consider 



