184 CALIFORNIA ACADEMY OF SCIENCKS. 



rapidit}' with which the germination takes place, and, in 

 Marsilia, for the length of time that the spores retain their 

 vitality. For studying the germination, species which 

 grow where they become entirel}' dried up after the spores 

 ripen, are best. Species like J/, quadrifolia, which is 

 strictl}' aquatic, are more difficult to germinate. J\f. vestita, 

 the common species of California, has proved a most 

 satisfactory form for study. Through the kindness of 

 Mrs. Brandegee a plentiful supph' of ripe fruits of this 

 species was placed at my disposal, and it was possible 

 for me to trace the development of the prothallium and 

 embryo in a most satisfactoiy manner. 



The earliest works on the Marsiliaceai are extremelv 

 imperfect and will not be further referred to. Hofmeis- 

 ter * was the hrst to recognize the real affinities of these 

 plants, but his accounts leave much to be desired. The 

 first account that was in any sense complete was that of 

 Hanstein,t which threw a good deal of light on the de- 

 velopment of both the prothallium and embryo, but in 

 regard to the former was very far from correct. Owing 

 to his methods of treating the delicate prothallium with 

 potash and other clearing agents, much of the structure 

 was destroyed, and very erroneous conclusions were 

 reached. Later, Arcangeli % and Sadebeck § corrected 

 some of the worst mistakes, and the waiter || later, with 

 the aid of more perfect modern histological methods, was 



* Hofmeister. The Higher Cryptogamia, pp. 325-327. 



t Hanstein. Die Befruchtung and Entwickhing der Ciattung Marsilia (jahr- 

 buch fur Wiss. Bot. 1865). 



t Arcangeli. Sulla Pilularia e Salvinia (Nuovo Giornale botanico Italiano, 

 vol. viii, 1876). 



^Sadebeck, in Schenck's Handbuch der Botanik, vol. i, p. 238. 



llCampbell. The development of Pilularia globulifera (Annals of Botany, 

 vol. ii, No. viii, Nov., 1888. Campbell — Einige Notizen uber die Keimung von 

 Marsilia .F.gyptiaca — lierichte der Deutschen botanischen Clesellschaft, 1888. 



