AND ELATERS OF MARCHANTIA POLYMORPHA. 105 



ccBCum), and often curved like a hook. At this epoch they contain colourless spherules 

 which subsequently disappear. 



" When the elaters are older they have acquired a yellow colour, and one would say that 

 each served as a sheath to two long, very narrow bands, rolled concurrently and parallel, 

 like a corkscrew, with very loose convolutions. There is an optical illusion here ; the 

 bands do really exist ; but instead of being free in the interior of the tube, they are an 

 integrant part of it." 



In his second memoir*, M. Mirbel gives an account of the development of the elaters 

 of Marchantia polymorpha : — " It (the sporangium) is at first merely a mass of tissue, 

 composed of utricles filled with green spherules. But when the pistil had attained the 

 degree of development last indicated, the internal utricles had become detached from one 

 another, while those of the superficies remained closely united, and constituted a balloon- 

 like sac, completely closed, in which the internal utricles were imprisoned. These were 

 not all of one kind ; some had been developed into long slender tubes, pointed at both 

 ends, which most certainly still adhered by one of these ends to the internal surface of 

 the sac; the others, in much larger numbers, polyhedral at first, had passed into a 

 spherical form by the gradual rounding off of their angles. To each utricle elongated into 

 a tube, a double series of utricles were feebly adherent. Both kinds were still filled with 

 green spherules. 



"As they advanced in age, the utricles composing the sac and those elongated into tube* 

 underwent modifications, to which I must draw the attention of physiologists." [Three 

 or four flattened rings, arranged parallel, appear on the walls of the cells of the sac ; these 

 become better defined, and at last acquire a yellow colour. My own observations on this 

 point agree perfectly with those of M. Mirbel.] " The utricles elongated into tubes only 

 differed from the others in form at first ; they then possessed a delicate, simple, diapha- 

 nous, entire, uncoloured, membranous wall, but they soon became thickened, lost then- 

 transparency, and became marked all round, throughout their whole length, with two 

 parallel streaks, closely approximated and describing helices. Then, increasing in size, 

 their streaks became slits which cut the wall of each, from one end to the other, into two 

 filaments, and the convolutions of these filaments separated, resembling the turns of a 

 corkscrew. Finally, the two filaments acquired a rusty yellow colour, and the metamor- 

 phosis was so complete, that if I had not followed the modifications, step by step, I 

 should now be afraid to say that these two filaments were at first one simple utricle ; but 

 the fact is constant, and I am convinced that whoever repeats the series of my observa- 

 tions, with the firm determination to let nothing escape which it is possible to see, will 

 arrive at the same result as myself." 



Bischoff gives no account of the development of the elaters, and evidently mistakes 

 their origin, for he saysf : — "Where we find among the spores, elaters which, arising 

 originally as elongated cells from the internal wall of the sporangium, He among the 

 parent-cells of the spores, I should rather compare them to the cellular filaments which 

 occur in the capsules of Mosses, e. g. in Buxbaumia, Funaria, &c, running across 

 between the outer and inner membranes of the sporangium ; and in Polytrichum, in part 



* Loc. cit. p. 382. f Bemerkungen iiber die Lebermoose ; Nova Acta Ac. Nat. Cur. xvii. p. 909 et seq. 



