68 DUDLEY MEMORIAL VOLUME 



Fimbriaria (Asterella) Calijornica, Hampe. 



Spores of this plant were collected at the beginning of the dry season, 

 late in April or in May, according to the time of ripening, from plants grow- 

 ing on a sandy-loam bank, not far from the laboratory. The spores were 

 kept in envelopes and pasteboard boxes in a case in the laboratory and were, 

 therefore, air-dry and well ventilated. As the humidity of the air runs low 

 during the summer dormant period, both in the laboratory and out of doors, 

 the spores were necessarily inactive for months. With greater humidity or 

 what would produce this inferior ventilation, their respiratory activities 7 

 would be greater and there would be danger that their germinating and 

 other powers might be impaired. For this reason I avoid keeping spores or 

 seeds which are to be used for germination in tightly-closed jars or bottles. 

 If it be necessary to protect them against mice, I use tins, the lids of which 

 close them loosely enough to permit more or less circulation of air. In this 

 way spore and seed deterioration is delayed and normal dormancy is main- 

 tained. 



The spores were sowed, as above described, on sterilized tile in black- 

 covered crystallizing dishes, on October 11, 1911. Of these, five were put 

 on turn-tables making two complete revolutions per minute, and three were 

 set on the shelf beside them. The crystallizing dishes standing on the shelf 

 were marked on the side away from the window, so that one might always 

 know the original exposure and the more easily maintain it. 



As previously shown 8 , the direction of the plane of division in the ger- 

 minating spores, and of growth in the germ-tube, is determined by the direc- 

 tion from which the light falls upon the spores. On the clocks, therefore, 

 the spores germinate in every direction, and the plantlets are erect from the 

 start. Germination actually begins almost at once, no doubt, but the evi- 

 dences of it are plainly visible within ten days after sowing the spores. In 

 the shelf cultures the plantlets are prostrate, growing toward the light as 

 single chains of chlorophyll-containing cells. In these latter cultures, as in 

 nature, the light falls upon the plantlets mainly from one direction, and the 

 plantlets react accordingly. After the plantlet has become a single chain 

 of several cells, the end cell repeatedly divides in such planes as to change 

 the plantlet to a conical shape. These little cones, with their apices pointing 

 away from the light and obliquely downward, grow both in length and in 

 diameter fairly symmetrical for a few weeks. After a time, however, they 



7 Babcock, S. B. Metabolic water ; its production and role in vital phenomena. 

 Research Bull. 22, Univ. Wis. Agric. Exp. Sta., March, 1912. 



8 Peirce, G. J. Annals of Botany, XX, p. 453+, 1906. 



