12 Brannon. — The Structure and Development of 



less glass gave much better results than those in open dishes, 

 living from ten to thirteen days, which was due, perhaps, to 

 the exclusion of dust and the maintenance of a lower tem- 

 perature. The average of results of experiments with carpo- 

 spores and tetraspores shows that they live for a longer time, 

 attain greater size, and possess a more vivid colour when kept 

 under blue glass than when covered with red, and in both 

 instances give more satisfactory results than those germinating 

 under the colourless glass. These conclusions, while not final, 

 give additional weight to the belief that this plant is par- 

 ticularly sensitive to light. 



Under the most favourable conditions (beneath blue glass), 

 the spores developed into young fronds of twenty-four cells ; 

 and on adult fronds collected, young plants of exactly com- 

 parable development were found growing in epiphytic fashion. 



With the addition of these and more advanced forms, it 

 was possible to pass in review the successive phases from the 

 unicellular spores to the fully-developed membranaceous 

 fronds. 



Not only does Grinnellia reproduce itself by means of 

 spores, but also vegetatively, in two ways. First, by the 

 method referred to above where proliferations arise from the 

 remnants of frayed fronds. Very many of these specimens 

 were collected in the latter part of the season from piles which 

 had been scraped earlier in the summer, at which time only 

 fragmentary fronds of Grinnellia had been left attached. 

 The second method of vegetative reproduction was observed 

 in small portions of the frond which had been severed 

 accidentally from the parent plant. These fragments, con- 

 taining a short portion of the midrib, attached themselves 

 by their cut ends to the bottom of the porcelain dishes, and 

 grew vigorously as long as they were supplied with the usual 

 favourable conditions. 



Development of Antheridia. 



In his work on the fructification of the Florideae, Dr. Schmitz 

 states that, in all cases examined, the reproductive organs 



