66 FERTILIZATION AND FRUIT-FORMATION IN CRYPTOGAMS. 



The investing leaflets at the summit of those stems which terminate in antheridia 

 are crowded close together; they are short, broad, and of a brownish-red colour, 

 and look like small floral-leaves seated upon a disc-shaped receptacle. Polytrichum 

 is a typical instance of the Mosses which exhibit a conspicuous contrast between 

 the investing scales of antheridia and those of amphigonia. The perich^tium in 

 individuals which produce only amphigonia possess an altogether different form 

 and arrangement of parts from the corresponding structure in antheridia-bearing 

 individuals. The difference is shown in Plate IX. The Polytrichum-siems, 

 which are seen in the picture standing up behind those terminating in flower-like 

 discs, have no antheridia, but send up slender bristles, on each of which is borne a 

 spore-case. These, however, are the products of amphigonia, which lie concealed 

 amongst the long green leaflets at the tops of the stems, and have there undergone 

 fertilization. 



As before said, there is a close resemblance between Muscineae and Characese as 

 regards the position of the ooplasm to be fertilized in the middle of the amphi- 

 gonium, the genesis and form of the spermatozoids, and, lastly, the process of fer- 

 tilization. But from the moment of fertilization the course of development is 

 altogether different. The fruits of Characess become detached from the mother- 

 plant, whereas those of Muscinese remain in connection with it, and this connection 

 is not merely mechanical but organic. The generation developed from the Moss- 

 fruit continues to derive the nutritive substances requisite for its growth and 

 completion from the mother-plant, and without the support of the latter it would 

 inevitably perish. The word support may here be used in a wide sense; for the 

 mother-plant is actually the bearer or stay of the new generation, which is produced 

 from the ooplasm converted by fertilization into an embryo, and it may be com- 

 pared to a tree with Mistletoe growing upon its boughs. In Characese the separate 

 stages of development are always quite distinct; the stage of maturity in par- 

 ticular being characterized by the falling away of the fruit from the mother-plant. 

 This is not the case in Muscinese. Since no separation in space takes place, it is 

 also difficult to establish time-limits and to say when the fruit has attained 

 maturity, and the difficulty is increased by the fact that no sufficient indications 

 are affiDrded by alterations of shape or colour. It is best to look upon the forma- 

 tion of fruit as being complete as soon as fertilization has taken place; from this 

 moment the ooplasm must be considered to be an embryo, and its envelopes to be 

 fruit-coats. Evidence in favour of this conception of the phenomenon is aflforded by 

 the circumstance that after the union of ooplasm and spermatoplasm development 

 is arrested, and a period of repose ensues, whereas both before and afterwards the 

 outward manifestations of change follow one another in rapid succession. A 

 description of the subsequent changes has been already given (see pp. 15, 16), and 

 we need only repeat here that the generation which springs from the Moss-fruit 

 develops spores and, after having scattered them abroad, dies away. 



The strongest likeness exists between the fruit-rudiments and antheridia of 

 Muscineffi and those exhibited by Ferns, Horse-tails, Ehizocarps, and Club-Mosses, 



