Britton and Taylor : Life History of Schizaea pusilla 3 



species of Lygodium, and by Anemia in the Cretaceous. Thus far 

 Schizaea is unknown in the fossil state. We may safely conclude, 

 however, that its maximum development in North America must 

 have been reached previous to the Glacial period, and that it is in 

 a degenerate condition and retrograding distribution in the only sur- 

 viving species, Schizaea pusilla, whose larger and more highly de- 

 veloped relatives exist now only in the tropics. 



Spores 



The spores of Schizaea pusilla measutfe 76—84 fi t are nearly 

 reniform (Fig. 1), and have a cuticulariz^d exospore which is al- 

 veolate (Figs. 2, 3) ; on the concave side there is a ridge extend- 

 ing nearly two thirds the length of the spore, formed by the exo- 

 spore having a fissure nearly its rfhole length (Fig. 4). It is 



■ 



through this slit in the exospore that the young tube emerges 

 when the spore germinates. 



The development of the gametophyte from the spore to the first 

 archegonium could not be followed in the laboratory ; but from 

 the laboratory cultures and the different stages of spore germina- 

 tion found in the soil brought up from New Jersey a fairly good 

 idea of the mariner and rate of growth may be drawn. 



Spores, from the plants collected in July and matured in the 

 greenhouse, were sown on September 5th ; on the 14th they were 

 found to be slightly green ; the first signs of germination were 

 seen on the 27th, when the spores contained some chlorophyl, 

 and two had started to send out a tube which extended 2 1 / jt 

 beyond the aperture (Fig. 5); chlorophyl was visible in the lengthen- 

 ing tube on the 8th and rhizoids were also found on that date ; 

 the first cross-wall was formed on the 10th ; on October 1st the 

 second wall was formed making a filament of two cells (Figs. 9, 10). 



On August 28th a spore was found in the sod of young plants 

 which had germinated and formed a small rhizoid, slightly brown, 

 with a curved apex and contained some chlorophyl, and a filament, 

 115 //in length, of two cells (Fig. 19), the cell at base was shorter, 

 about twice as long as broad, containing chlorophyl with no special 

 arrangement ; the other cell was nearly four times as long as 

 broad, the chlorophyl denser at the apex and a newly formed wall 

 (Fig. 19, a). The density of the chlorophyl increased at the 



