474 Yasui . — On the Life-history of Salvinia natans . 
meantime the nuclear reticulum becomes more prominent, and the nucleus 
begins to elongate. The elongated blepharoplast attaches itself to the 
dorsal side of the nucleus, which now begins to coil. The elongating nucleus 
which forms the greater part of the spermatozoid-body makes a coil of 
about two turns (PL XLI, Figs. 50, 51, 53). The numerous cilia evidently 
originate from the blepharoplast attached to the dorsal side of the nucleus. 
The spermatozoid, when it comes out from the sperm-cell, swims about 
by means of cilia attached to the anterior dorsal side of its body, making 
two spiral coils. It carries a vesicle in the hinder end of its body, which 
contains several small starch-grains ; the vesicle may, sooner or later, be 
detached from the spermatozoid. 
Macrospore Formation. 
The macrosporangium-initials appear at the apex of the young sporo- 
carp (PL XLI I, Fig. 54). They are characterized by denser cytoplasm and 
larger nuclei. Each initial is cut off at the base by two oblique walls, which 
are more or less perpendicular to each other, and thus the young stalk is 
formed. The third wall, parallel to the first oblique wall, is then formed ; the 
last-formed cell corresponds to the basal cell, the first primary wall-cell of 
the young microsporangium. The fourth wall, parallel to the second 
oblique wall of the stalk, is then formed, being soon followed by a peri- 
clinal wall, thus forming an archesporial cell and three primary wall-cells 
(Fig- 55)- 
Three primary cells of the tapetum are cut off by periclinal walls from 
the archesporial cell (Fig. 56). In the meantime the wall-cells are divided by 
repeated radial divisions. The primary tapetal cells also undergo repeated 
radial divisions, and one layer of the tapetum is formed (Figs. 57-60). 
According to Juranyi (73) the tapetum usually consists of two layers, 
as the following statement shows : ‘ Die Mantelzellen theilen sich namlich 
in tangentaler Richtung ; dieser Theilungsweise sind aber dieselben zu 
dieser Zeit gewohnlich nur einmal unterworfen, in Folge dessen der Mantel 
in der Regel nur zweischichtig wird (Taf. II, Fig. 22).’ This statement is 
adopted by Campbell in his revised edition of ‘ Mosses and Ferns \ Hein- 
richer (’82), however, mentions that the tapetum is usually of a single layer. 
I was not able to confirm the statement of Juranyi, and no case was met 
with in which the tapetum consisted of two layers of cells. 
Simultaneously the central cell continues to divide (Figs. 57~59)> anc * 
after the third division it reaches the spore-mother-cell stage ; so there are 
eight spore-mother-cells in one macrosporangium. The spore-mother-cells 
are easily distinguished from the surrounding cells by denser granular 
cytoplasm and larger nuclei (Fig. 59). There are two different statements 
concerning the number of the macrospore-mother-cells. According to 
