24 



what appeared to be other segments of the same cluster, each plant 

 from a segment. The second frond of two of these seven plants is 

 plainly dichotomous, a frond of another is slightly eccentric, the 

 other fronds are normal. One of the three earlier plants has from 

 the first shown a striking tendency to produce abortive fronds, and, 

 so far as one can tell from plants barely an inch and a half high, ap- 

 pears truly intermediate between young typical plants of marginale 

 and of cristatum, as does a second of the plants developed last 

 fall.* This plant has produced one abortive and one markedly ec- 

 csntric frond. The fronds of the third of last fall's plants are all 

 normal and the character of the plant is like that of pure cristatum. 

 In May, about the time that the seven later plants appeared, eight 

 more developed from other prothalli in the same pot. All have 

 normal fronds. These later plants cannot be the result of self- 

 fertilization before the cutting; the time that has elapsed is too 

 great, and the segments from which many or all have sprung were 

 not then in existence. I have not cared to disturb them in order to 

 look for evidence of asexual growth, but it is hardly likely that all 

 fifteen have arisen in that way. What they will prove to be, may 

 throw some light on the question of whether or no the missing 

 organs are reproduced. 



In order to obtain a reciprocal cross, I cut, in October, 1899, 

 archegonial sections of marginale and antheridial sections of cris- 

 tatum. Because the time was so long since the spores had germi- 

 nated, I feared that some of the archegonia might have become fer- 

 tilized, and so isolated both sections for a time in separate pots. 

 Four plants developed within a month and were thrown away. 

 Since no more plants appeared, I planted, in December, the two 

 kinds of sections together. Both kinds had branched freely. In 

 March, two segments of one section developed what appeared to be 

 a broad, much thickened, archegonial cushion of tissue, covered 

 with a mucilaginous liquid. This soon dried, and the cushions 

 swelled outward into points. The point in one cushion devel- 

 oped into a horizontal cylindrical process that is still lengthening, 

 and has flattened at the end into a fan-shaped lobate growth. A 



* These two plants have since shown marked evidence of hybridity. Their 

 rootstocks are caudiciform, like rootstocks of cristatum y. marginale Davenp. 

 The fronds of one are a mean between those of its parents. Of four fronds at 

 present 011 the other, one has spinulose margins, like young cristatum. one 

 large blunt lobes, like young marginale, while the remaining two are interme- 

 diate in form. 



December 6, 1900. 



