122 REPORT — 1851. 



planation of these relations to be urged as a valid argument against their 

 existence, and I trust that this imperfect report may be the means of attract- 

 ing new investigators to a subject which presents so many points of interest 

 and importance. — July 3rd, 1851. 



Postscript. — Since the above Report has been in print Dr. W. Hofmeister 

 has published his promised work upon ihe higher Cryptogams*, which con- 

 tains an elaborate series of researches upon this subject. He there confirms 

 all his previous statements, and all the essential particulars given by Su- 

 minski, Nageli, Mettenius, &c., excepting i\\e facts of the impregnation by 

 means of the spiral filaments or spermatozoids, which however he considers it 

 warrantable to assume. His speculations as to the relation of the Conifers 

 to the Lycopodiaceae, as shown by the development of the embryo, are very 

 interesting. We can only claim space to indicate the general results of his 

 work as given in the concluding summary: — " The comparison of the course 

 of development of the Mosses and Liverworts on the one hand, with the 

 Ferns, Equisetaceae, Rhizocarpeae and Lycopodiaceae ou the other, reveals 

 the most complete agreement between the development of the fruit of the 

 former and the developmentof the embryo of the others. The archegonium 

 of the Mosses, the organ within which the rudiment of its fruit is formed, 

 resembles perfectly in structure the archegonium of the Filicoids (in the 

 widest sense), that part of the prothallium in the interior of which the embryo 

 of the frondescent plant originates. In the two great groups of the higher 

 Cryptogams, one large central cell originating free in the archegonium, gives 

 origin by repeated subdivision to the fruit in the Mosses, and to the leafy 

 plant in the Filicoids. In neither of them does the subdivision of this cell 

 go on, in both does the archegonium become abortive, if spermatic filaments 

 do not reach it at the epoch when it bursts open at the apex. 



" Mosses and Filicoids thus afford one of the most striking examples of a 

 regular alternation of two generations widely different in their organization. 

 The first of these, produced by the germinating spore, developes antheridia 

 and archegonia, sometimes few, sometimes many. In the central cell of the 

 archegonium, in consequence of a fertilization through the spermatozoids 

 emitted from the antheridia, becomes developed the second generation, des- 

 tined to produce spores, which are always formed in a number much greater 

 than that of the rudimentary fruits of the first generation. 



" In the Mosses the vegetative life is exclusively committed to the first, 

 the production of fruit to the second generation. Only the leafy stem pos- 

 sesses roots; the spore-producing generation draws its sustenance from the 

 foregoing. The fruit is usually of shorter duration than the leaf-bearing 

 plant. In the Filicoids the opposite condition obtains. It is true the pro- 

 thallia send out capillary rootlets ; those of the Polypodiaceae and Equise- 

 taceae under all circumstances, those of the Rhizocarpeae and Selaginellae 

 frequently. But the prothallium has a much briefer existence than the 

 frondescent plant, which in most cases must vegetate for several years be- 

 fore it comes to bear fruit. Yet the contrast is not so strong as it appears 

 to be at first sight. The seemingly unlimited duration of the leaf-bearing 

 Moss-plant depends upon constant renovation {verjiingung). Phaenomena 

 essentially similar occur in proliferous protliallia of the Polypodiaceae and 

 Equisetaceae. The structure of the lowest Mosses (^Anthoceros, Pellia) is 



* Vergleichende Unteraucftungen der Keimung, Entfaltung und Fmchtbildung hoherer 

 .Kryptogamen {Moose, Farm, Equisetaceen, Rhizocarpeen und Lycopodiaceen) und der Sa- 

 menbildung der Coniferen. 1851, Leipsic, Hofmeister, 4to, pp. 180, tt. 33. 



