REPRODUCTION, VEGETABLE (VEGETABLE OVUM). 



238 



nema),* resembling in all its relations to the 

 future plant, the mycelium of the Fungi and 

 Lichens. 



73. First period. Germination of the spore. ^ 

 The spore of the Mosses is a nucleated cell, 

 the solid contents of which are granular, and 

 consist of protein compounds, starch and dex- 

 trine. From the budding out of its membrane, 

 results a hollow filament, which, as it lengthens, 

 divides by a succession of transverse septa. 

 It then begins to branch in all directions, 

 each branch resembling the parent, and rami- 

 fying in the same manner. Hence results an 

 entangled network of filaments of a brilliant 

 green colour, which spreads over the moist 

 surface on which the spores have been sown. 

 At length some of the filaments are observed 

 to give off lateral branches which differ from 

 those previously formed in being more slender 

 and containing less chlorophylle. In some of 

 these the terminal cell, after dividing four or five 

 times, becomes globular, and is transformed 

 into the rudiment of a leafy axis. 



74. Development of the antheridia and arche- 

 gonia. These organs are usually found in 

 groups, which are situated either at the termi- 

 nation of the stem or branches, or in the axils of 

 the leaves. In either case they are surrounded 

 (with the exception, in many genera, of the 

 axillary antheridia) by special arrangements of 

 modified leaves (involucres). Those involucres 

 which surround the antheridia are called 

 perigonia, and are composed of leaves much 

 smaller than the ordinary leaves of the stem. 

 Those leaves which enclose the archegonia, 

 small at first, attain a large size as the fruit 

 approaches maturity. In some (hermaphro- 

 dite) mosses, both antheridia and archegonia 

 are contained in one involucre. 



75. In the very diminutive plants belonging 

 to the genus Phascum, which we select as ex- 

 amples on account of their great simplicity of 

 structure, the groups of archegonia are termi- 

 nal, those of antheridia usually axillary. The 

 growing extremity of the stem (terminal bud) 

 or axillary bud, when destined to bear repro- 

 ductive organs, instead of developing to a new 

 axis, becomes flattened in such a manner as 

 to present a slightly convex disc, which takes 

 the place of its conical growing extremity. It 

 is upon the surface of this disc that the rudi- 

 ments, whether of antheridia or of archegonia, 

 originate, by a process precisely similar to that 

 which we have described in the commencing 

 development of the antheridia of Anthoceros. 

 The rudiment consists, as in Anthoceros, 

 of four columns of cells, combined so as to 

 form a cylindrical club-shaped body. The 

 development and ultimate form of the arche- 

 goriium corresponds so completely with what 

 has been described in the Jungermanniae, that 



* From the very recent observations of Gronland 

 (Mem. sur la Germination des Spores de quelques 

 Hepatiques, Ann. des Sc. Nat. 3 m * S. xx.), it appears 

 that among the higher Hepaticae with cut leaves, 

 the first result of germination is always a branched 

 and septate filamentous protonema, resembling that, 

 of the Mosses in its relation to the leafy stem. 



f Hofmeister, loc. cit. pp. 6571.; Bruch & 

 Schimper, Bryologia Europaea, Fasc. i. p. 5. 



it is unnecessary to describe it. The fully 

 formed antheridium of Phascum is a club- 



Fig. 165. 



Section of termination of fruitful stem of Phascum 

 cuspidatum,oQ diam. 



On the right a female, on the left a male inflo- 

 rescence. From the slightly convex surface 

 which forms the summit of the stem, spring in 

 the one case the archegonia, in the other the 

 antheridia, along with numerous jointed fila- 

 ments. 



shaped body of about the same length as the 

 archegonium, and consists of a central mass of 

 minute quadrangular cells, which is enclosed 

 by a single layer of tabular cells, in contact 

 with each other by their edges. Shortly be- 

 fore the antheridium arrives at maturity, the 

 quadrangular cells, each of which contains a 

 spiral filament enclosed in a lentil-shaped 

 vesicle, are dislocated. This is followed by 

 the total disappearance of their membranes, so 

 that the vesicles float free in the cavity of the 

 now ripe antheridium. No sooner is this the 

 case than the organ gives way at its summit, 

 and discharges its contents in the form of an 

 intestine-like coil of mucus, consisting of the 

 lenticular vesicles with their contents. Soon 

 after, this is dissolved, and the spiral filaments 

 commence their active motions. 



76. Development of the fruit. The early 

 stages correspond with those described in Pel- 

 lia. At a period when the lower dilated portion 

 of the archegonium is about fivetimes its ori- 

 ginal length, the young fruit, which is a fusiform 

 cellular body, does not occupy more than its 

 upper half. In the meantime the cells form- 

 ing the tissue subjacent to, or in the immediate 

 neighbourhood of, the base of the fructified 

 archegonium, have multiplied with such acti- 

 vity, that the end of the stem has again assumed 

 the form of a cone, on the summit of which 

 the fruit is borne, while the aborted archegonia 

 are scattered round its sides. In its further 

 development, the fruit grows much more 

 rapidlv in length than in breadth, and in con- 

 sequence of its extension upwards being op- 

 posed by the resistant structure of the canal 

 of the archegonium, its lower end presses 

 downwards in such a manner as to cause the 

 absorption, not only of the cellular tissue of 

 the archegonium, which is subjacent to it, but 

 of that of the conical summit of the stem. In 



