860 THE "PRO-EMBKYO" OF CHARA. 



A very obvious objection is at once suggested by this table, viz., 

 that if it be correct the sporophore of Chara is represented by an 

 organ which has never been known to produce spores. It must 

 not be forgotten, however, that the transition from the sporophore 

 to the oophore in plants which present a well-marked alternation 

 of generations is not necessarily effected by means of spores. The 

 recent researches of Pringsheim '•' and of Stahl f have shewn that 

 the seta and the sporogonium {i.e. the sporophore) of |a Moss may, 

 under certain conditions, give rise to a protonema upon which the 

 moss-plant (oophore) is subsequently developed as a lateral out- 

 growth. From the observations of Miiller | we know that the 

 protonema of a Moss is merely the simplest possible form of its 

 leaf-bearing stem. These facts warrant the assertion that a direct 

 transition from the sporophore to the oophore can be effected 

 in Mosses without the intervention of spores. It is not so para- 

 doxical, therefore, as it api3ears to be at first sight, to apply the 

 term " sporophore " to an organ which does not actually produce 

 spores. It may be inferred that the condition which is accidental 

 in Mosses is permanent in Chara, in which i^lant the sporo^Dhore 

 remains rudimentary, producing no spores, but giving rise to the 

 oophore by lateral budding from one of its cells. 



The vegetative reproduction by means of the " pro-embryonic 

 branches " — or, as should now be said, " embryonic branches " — 

 which has been described in detail by Pringsheim, and which is of 

 common occurence in Chara, affords some indirect but valuable 

 support to the views here advanced. These embryonic branches 

 spring from the nodes of the stem, and closely resemble the 

 embryo in theii- structure. Like the embryo, an embryonic branch 

 gives origin to a sexual plant by a process of budding from one of 

 its cells which hes behind its apical cell. Expressing these facts 

 in general terms this process may be described as the development 

 of numerous si)orophores (embryonic branches) by budding from 

 the oophore (C7?a;-a-plant), as an instance, that is, of a transition 

 from an oophore to a sporophore without the intervention of sexual 

 reproductive organs (Apogamy, Be Banj). Other instances of this 

 occur among Ferns. It has been found § that the prothaUus 

 (oophore) of certain Ferns [Aspidium filLv-inas cristatiun, Aspidium 

 falcatuni, Pteris creticd) gives rise to the fern-plant (sporophore) 

 by a process of budding without the development of any sexual 

 reproductive organs, and that this is the only means by which 

 these Ferns are reproduced. 



It appears from the foregoing facts and deductions (1) that a 

 well-marked alternation of generations occurs in the life-history of 

 Chara, and (2) that the C7««rrt-plant with its reproductive organs is 



* ' Jahrb. fiir wiss. Bot.' Bd. xi. 1877, p. 1. 



+ ' Bot. Zeitg.' 1876. 



\ ' Die Sporenvorkeime etc., der Laubmoose.' * Arb. d. bot. Inst, in Wiirz- 

 burgh,' Bd. I., Heft.iv., 1874. 



§ Farlow, on asexual growth from the prothaUus of Pteris cretica. ' Quart. 

 Journ. Mic. Sci.', vol. xiv., 1874. 



De Bary ; Ueber apogame Fame, .fee. ' Bot. Zeitg.', 1878. 



