146 



SCIENCE-GOSSIP 



a little differently ; perhaps the unusually hot 

 summer had abbreviated the normal course. Be 

 this as it may, early in November I gathered 

 acorns already sprouting, and in December about 

 half of the piled-up acorns in a shady corner 

 of the verandah, without any spring warmth, 

 without any moisture, and without any soil to 

 penetrate, had already long radicles, and the finest 

 of them, set to grow in the glasses, throve well all 

 through the summer 

 of 1894, till the end 

 of October, when 

 inexorable circum- 

 stances parted me 

 from them. 



Many of the acorns 

 of 1893 "were of un- 

 usual size, quite an 

 inch long, and pro- 

 portionately broad. 

 They fell, some with 

 and some without 

 the cup or cupule, 

 which is no part of 

 the fruit itself, but 

 only a mass of har- 

 dened bracts of the 

 floral envelope. The 

 acorn is a polished 

 dark brown or lea- 

 ther-coloured, egg- 

 shaped fruit. Its 

 broad flat end that 

 lies in the cup is 

 marked by a large 

 round scar, the re- 

 mains of the attach- 

 ment of acorn and 

 cup ; the scar is 

 rough from the 

 breakage of the little 

 pipes or vessels 

 which traversed the 

 cupules from the 

 stem to the fruit. 

 The free end of the 

 acorn is pointed 

 with a little knob, 

 the remains of the 



stigma of the past and gone flower of Spring. 

 The polished hard coat of the acorn, marked with 

 fine longitudinal lines, is the covering of the fruit, 

 the pericarp ; inside this is a papery membrane, 

 the inner pericarp. In the ripe fruit both are 

 dead structures, existing as protecting coverings 

 to the seed within, which is now loose and free 

 from them. On shaking it may be heard to rattle 

 about ; it was at first attached by the broad end 

 by the same connecting pipes that ran through 



Fig. 2. — 1, section of half of embryo ; 2, germinating embryo 

 with one cotyledon removed ; 3, advanced stage of germina- 

 tion ; s, pericarp; sh, testa; b, plumule; st, petiole of 

 cotyledon ; he, hypocotyl; c, cotyledons; /, vascular bundle; 

 w, primary root. (After Lacks.) 



the cup from the twig. The pipes too are 

 shrivelled and dead and broken across, their 

 use being past. The seed is not much smaller 

 than the fruit which it fills up loosely, of the 

 same shape, and covered with brown papery 

 membrane, its own coat or testa. It is horny and 

 hard, and is made up of two halves lying closely 

 pressed together, face to face, from the top of the 

 acorn to the bottom. These two halves or cotyle- 

 dons are not quite 

 separate or free from 

 each other, they are 

 united to a tiny body 

 lying embedded and 

 pressed between 

 them at the pointed 

 end of the seed, a 

 body that is of itself 

 so small that it is 

 easily overlooked. 

 The larger end of 

 this small embryo 

 is the radicle point- 

 ing upwards to the 

 apex of the acorn ; 

 the smaller end 

 turned down is the 

 plumule, the origin 

 of the stem and 

 leaves of the oak, 

 as the radicle is the 

 origin of its root 

 system. Each coty- 

 ledon is united to 

 the tiny embryo by 

 a minute stalk. 

 Thus the testa of the 

 large seed is filled 

 up by two immense 

 cotyledons, a tiny 

 radicle and a tinier 

 plumule, the tip of 

 the radicle lying 

 just inside the mem- 

 brane covering the 

 seed and pointing 

 outwards. 



Thin sections of this 

 seed placed under 

 the microscope display polygonal cells of thin walls 

 tightly packed with granule-like contents. The 

 whole embryo consists almost entirely of this 

 fundamental tissue. Surrounding the embryo and 

 following all its shape is a layer of flattened cells 

 fitting close round it as a glove, and this is the 

 outer layer of the young plant, the epidermis. 

 Where the sections are cut across the cotyledons, 

 or radicle, or plumule, there are seen certain minute 

 specks, the cut surfaces of fine cords of long and 



