480 Yasui. — On the Life-history of Salvinia natans . 
I am indebted to Dr. K. Miyake for his kind suggestions and advice 
during the progress of this work. 
Note .- — After this had been written, Professor Arnoldis paper, ‘ Beitrage 
zur Morphologie der Keimung von Salvinia natans ,’ appeared in Flora 
(Bd. c, pp. 132-139, 1909). His results agree with mine in essential points, 
except in one important matter, i.e. the number of chromosomes. He 
gives four as the chromosome number of the gametophytes and eight for 
the sporophyte. I have found, however, that the number is twice as many 
as that given by Arnoldi, being eight and sixteen respectively. 
Literature cited, 
Arcangeli, G. (’ 76 ) : Sulla Pilularia e Salvinia. Nuovo Giornale Botanico Italiano, viii, 1876, 
p. 320. 
Bauke, H. ( 79 ) : Einige Bemerkungen liber das Prothallium von Salvinia natans. Flora, lxii, 
1879, p. 209. 
Belajeff, W. (’ 98 ) : Ueber die mannlichen Prothallien der Wasserfarne (Hydropterides). Bot. Zeit., 
lvi, 1898, p. 141. (The paper was published in Russian in 1892.) 
Campbell, D. H. (’ 87 ) : Zur Entwickelungsgeschichte der Spermatozoiden. Berichte der deutsch. 
Bot. Gesellsch., v, 1887, p. 120. 
(’ 65 ) : Mosses and Ferns. 2nd edition. New York, 1905. 
Heinricher, E. (’ 82 : Die naheren Vorgange bei der Sporenbildung der Salvinia natans ver- 
glichen mit der der iibrigen Rhizocarpeen. Sitzb. der k. Akad. der Wiss. Wien, lxxxvii, 
1. Abt., 1882, p. 494. 
Hofmeister, W. (’ 51 ) : Vergleichende Untersuchungen der Keimung, Entfaltung und Fruchtbil- 
dung der hoheren Cryptogamen, etc. Leipzig, 1851. 
(’ 57 ) : Beitrage zur Kenntniss der Gefass-Kryptogamen. II. Abhandl. d 
Mathem.-Phys. Classe d. Konigl. Sachs. Gesell. d. Wiss., p. 603, 1857. 
Juranyi, L. (’ 73 ) : Ueber die Entwickelung der Sporangien und Sporen von Salvinia natans. Berlin, 
i 873 - 
Mettenius, G. (’ 46 ) : Beitrage zur Kenntniss der Rhizocarpeens. Frankfurt a. M., 1846. 
Prantl, K. (’ 79 ) : Zur Entwickelungsgeschichte des Prothalliums von Salvinia natans. Bot. Zeit., 
i 879 > p. 425* 
Pringsheim, N. (’ 63 ) : Zur Morphologie der Salvinia natans. Jahrb. fiir wiss. Botanik, iii, 1863, 
p. 484. 
EXPLANATION OF PLATES XLI-XLIII. 
Illustrating Miss Yasui ’s paper on Salvinia natans. 
All figures are drawn with the aid of a camera lucida, from microtome sections. 
PLATE XLI. 
Fig. 1. Longitudinal section of the initial cell of a macrosporangium, x 600. 
Fig. 2. Longitudinal section of the initial cell of a microsporangium which is cutting off 
a stalk-cell, x 600. 
Fig* 3* The first wall-cell ( [w t ) is cut off from the apical cell, x 600. 
Fig. 4. The second wall-cell (w 2 ) is cut off from the apical cell, x 600. 
