110 REPORT— 1851. 



which I have not seen, but depend on analyses of it pubHshed in the ' Bota- 

 nische Zeitung*,' and the 'Flora' for 1851 1> and further in a letter from 

 Dr. Mercklin to M. Schaclu*|;, which appeared in the ' Linnaea ' at the close 

 of last year. 



He differs in a few subordinate particulars from M. Schacht in reference 

 to the development and structure of the ^^rothallium or pro-embryo, and of 

 the antheridia and spiral filaments ; but these do not require especial men- 

 tion, except in reference to the vesicular end of the spiral filament described 

 by Schacht, which Mercklin regards as a remnant of tlie parent vesicle, from 

 which the filament had not become quite freed. The observations referring 

 to the so-called ovule and the supposed process of impregnation are very im- 

 portant ; they are as follows : — 



" 1. The spiral filaments swarm round the * ovule ' in numbers, frequently 

 returning to one and the sajne organ. 



" 2. They can penetrate into the ' ovule.' This was seen only three times 

 in the course of a whole year, and under different circumstances ; twice a 

 spiral filament was seen to enter a still widely open young ' ovule,' then 

 come to a state of rest, and after some time assume the appearance of a 

 shapeless mass of mucilage ; t1ie third case of penetration occurred in a fully- 

 developed ' ovule,' through its canal ; it therefore does not seem to afford 

 evidence of the import of the spiral filament, but certainly of the possibility 

 of the penetration. 



" 3, In the tubular portion of the ' ovule,' almost in every case, peculiar 

 club-shaped, granular mucilaginous filaments occur at a definite epoch, 

 these filaments, like the spiral filaments, acquiring a brown colour with 

 iodine. These mucilaginous bodies sometimes exhibit a twisted aspect, an 

 opake nucleus, or a membranous layer, peculiarities which seem to indicate 

 the existence of an organization. 



" 4. These club-shaped filaments are swollen at the lower capitate extre- 

 mity, and have been found in contact with the ' embryo-sac ' or globular cell 

 which forms the rudiment of the future frond. 



" 5. The spiral filaments, which cease to move and fall upon the prothal< 

 lium, are metamorphosed, become granular and swell up." 



Hence the author deduces the following conclusions : — 



" That these clavate filiform masses in the interior of the ' ovule' are trans- 

 formed spiral filaments, which at an early period, while the ovule was open, 

 have penetrated into it; which leads to the probability that — 



" 1. The spiral filaments must regularly penetrate into the 'ovules,' and 



" 2. They probably contribute to the origin or development of the young 

 fruit frond (or embryo). In what way this happens the author knows not, 

 and the details on this point given by Count Suminski remain unconfirmed 

 facts." 



An important point in this essay is the view the author takes of the whole 

 process of development in this case. He regards it as not analogous to the 

 impregnation in the Phanerogamia, since the essential fact is merely the de- 

 velopment of a frond from one cell of the prothaUium, which he considers 

 to be merely one of the changes of the individual plant ; while all the other 

 authors who have written on the subject, with the exception of Wigand, call 

 the first frond, with its bud and root, an embryo, and regard it as a new in- 

 dividual, or at all events a distinct member of a series of forms constituting 

 collectively the representatives of the species. 



* Botanische Zeitung, vol. xxxiii. 1850. t Flora, vol. Mxiii. p. 696, 1850. 



X Linnsea, vol. xxiii. p. 723. J 850. 



