STRUCTURE.] DEVELOPMENT OF POLLEN GOURD. 353 



of this plant is about a Hue in length, each lobe of the anther 

 is entirely composed of cellular tissue, the bladders of which 

 present in general a pentagonal or hexagonal figure more or 

 less regular when cut across. In every cell, without excepting 

 even those which constitute the superficial layer of the lobe, 

 are certain loose particles, of such extreme minuteness that a 

 magnifying power of 500 or 600 diameters is required to exa- 

 mine them satisfactorily. I cannot compare them to anything 

 better than to little transparent bladders, nearly colourless, 

 more or less rounded, and of an equal size. I examined the 

 cells of the lobe of the anther one by one ; and I affirm that, 

 at this early period, there is no trace of either the cells of the 

 anther or of the grains of pollen. The whole of the tissue is 

 perfectly uniform. In a flower-bud, but little larger than the 

 first, I remarked on each side of the medial line of the slice a 

 group, consisting of a few bladders, which were rather larger 

 than the others, but otherwise like them. These larger bladders 

 I propose to call pollen- cells, seeing that it is in their inside that 

 the pollen is organised. In flower-buds, from 1| to 2 lines 

 in length, some remarkable changes were observable. The 

 pollen-cells had become larger ; their granules were so much 

 multiplied that they were grouped and packed in opaque 

 masses, and wholly filled the cells. These cells and granules 

 together constituted a greyish body, joined to the rest of the 

 tissue by the intervention of a cellular membrane, a sort of 

 integument which, notwithstanding its organic continuity with 

 the surrounding parts, was readily distinguishable ; for while 

 the bladders of the surrounding parts lengthened parallel to 

 the plane of the surface, and to the plane of the base of the 

 anther, those of the integument lengthened from the centre 

 to the circumference. In anthers a little further advanced, 

 the sides of the pollen-cells, instead of being thin and dry as 

 they had previously been, acquired a notable thickness, and 

 their substance, gorged with fluid, resembled a colourless 

 jelly. The cellular integument continued to adhere by its 

 outer face to the lining of the cell of the anther, and by its 

 inner face to the tissue formed by the pollen-cells. Three and 

 a half or four lines of length in the flower-bud corresponded 

 with a phenomenon altogether unexpected. At first the 



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