68 A FEW LAST WORDS ON CHAEA. , 



the * Journal ' for Dec. 1878. This botanist dissents from the 

 view adopted by Pringsheim and myself that the so-called * pro- 

 embryo ' of Chara is homologous to the protonema of MuscinecB. 

 While admitting the apparent cogency of some of his objections, 

 which deserve at all events a very careful consideration, I am 

 quite unable to adopt his view that this organ is the true embryo 

 of the plant. The first division of the central cell of the germin- 

 ating oosi)ore of Chara is, as has frequently been described, into 

 three cells, a large basal and two apical cells. The basal cell 

 appears to play the part (functionally but not homologically) of 

 the endosperm or prothallium, in supplying the young plant with 

 nutriment. From one of the two apical cells is produced the so- 

 called ' j)i"o-6mbryo ' ; fi'om the other the first root ; and it appears 

 to me unimportant for our present purpose whether we call this a 

 primary or an adventitious root. Now I know of no better 

 definition of the term embrj^o than that of Sachs, (/ Text Book,' 

 Englished., p. 421): — "The [first] residt of the develoxoment of the 

 oospore" ; and to alter the use of a term the acceptation of which has 

 hitherto been practically universal, by limiting it, in a particular 

 case, to the result of the development of a small portion only of 

 the oospore, seems to me an innovation open to grave objection. 

 Should Mr. Vines's view of this structure not be accepted, his 

 assumption of an alternation of generations in Chara will also fall 

 to the ground. The fertilised oospore of Chara develops into the 

 sexual individual just as (disregarding minor differences) the spore 

 of a moss does ; the whole of the x^rocesses which take place in the 

 moss between the development of the embryo and the germination 

 of the spore — in other words, the whole of the sporophore — 

 being sui)pressed in the case of Chara. In assuming the existence 

 of a sporophore which has never been known to produce spores, 

 the writer evidently perceives that he is advancing a proposition 

 w^hich will not be accepted unless supported by the most cogent 

 arguments. The analogies he brings forward are the production, 

 under abnormal circumstances, of a protonema from the seta of 

 mosses, and the production of certain species of fern by a process 

 of non- sexual budding from the prothallium. In stating that 

 '' this is the only means by which these ferns are reproduced," Mr. 

 Vines has possibly overlooked that Farlow states " In the present 

 instance certain examples [of Fteris serrulata] bore archegonia with 

 embryonal outgrowth" ; and in his elaborate paper on Apogamous 

 Ferns in the 'Botanische Zcitung ' (1878, p. 449 et seq.) De Bary 

 says tlmt Aspleniumfalcatum produces perfectly formed archegonia, 

 which it is quite possible may be occasionally fertilised, although he 

 had not observed this to be the case, either in this species or in the 

 others on which his observations were based. To establish the 

 existence of a ' nou-sporiferous sporophore,' occurring normally 

 thoroughout a whole class, w^ould seem to requh-e further proofs 

 than the analogy of a few morbid and exceptional developments. 

 I do not think therefore that sufficient reason has been shown 

 for departing from the following statement : — In MuscinecB 

 and Vascular Cryptogams we have the typical alternation of 



