206 ON THE STRUCTURE AND AFFINITIES OF CHARACE.E. 



the unimpregnated female organ of Chara — the homologue of the 

 archegonium of the other higher Cryptogams — as a " sjDorangium." 

 It would be possible also to draw other analogies between the 

 modes of vegetative reproduction in Cliaraceff. and in Mosses. 



Into the structure of the reproductive organs (archegonia and 

 antheridia, or nucules and globules) of CharacecB it is needless to 

 enter in detail. Although ver}^ different in many non-essential 

 points, there is no essential difference in the process of fertilisation 

 in CharacecB on the one hand and in Muscinece and Vascular 

 Crj^togams on the other hand. A female organ or carpogonium 

 of somewhat complicated structure contains within it a cell, the 

 contents of which constitute the "oosphere," while a more or less 

 open channel leads down to this central cell from the apex of the 

 carpogonium. Impregnation takes place by the coalescence with a 

 hyaline portion of this oosphere, of antherozoids consisting of 

 minute corkscrew-shaped threads of protoplasm, which escape 

 from an antheridium of complicated structure ; the result being 

 the development out of the fertilised germ- cell of a single 

 *' oosi^ore," or rudimentary embryo. 



The most essential point in which CharacecB do exhibit a 

 departure from all the higher Crj^^togams is the absence of any 

 true alternation of generations. In none of the other MuscinecB, 

 nor in Vascular Cryptogams, does the " oospore," or fertilised 

 germ-cell, germinate in the soil and give rise immediately to a 

 plant like the one which produced it, without the intervention of 

 intermediate non- sexual germinating spores. If, however, we are 

 justified — as I have attempted to show that we are — m considering 

 the "pro-embryo" as an integral part of the sexual generation, 

 this is the case with Chara. But this again would" seem to be 

 determined by habit, a true alternation of generations being rare 

 among aquatic plants. The so-called "spore " of CharacecB unites, 

 in fact, the properties of an " oospore " produced by impregnation, 

 and of a non-sexual " spore " capable of germination. To complete 

 the cycle of generations, we should expect the oospore to develope 

 into an intermediate structure, — the non-sexual generation, — the 

 development of which would terminate with the production of 

 germinating spores. May we not, then, regard the Characece as an 

 abnormal form of Muscinece, — i. e., of Cellular Cormophytes, — 

 aquatic in their habit, in which the formation of the non- sexual 

 generation is altogether suppressed ? 



Since writing the above, my attention has been called to two 

 recent papers relating to the structure and affinities of Characea. 

 Trevisan, 'in his "Conspectus Ordinum Prothallophytarum " 

 (' Bull. Bot. Soc. Belg., 1877, p. 4), includes in his second "region" 

 of Anthoyaime the two sub-divisions of Bryophi/ta: and PhycophytcB, 

 the first of which embraces Miisci and Hepaticce, the second 

 Characece only. Celakovsky has a paper in ' Flora ' (1878, p. 49 et 

 seg.), " Ueber die morphologische Bedeutung der sogenannten 

 Sporensprosschen der Characcen,'' in which he objects to the use of 



