Yasui, — On the Life-history of Salvinia natans . 475 
Juranyi there are sixteen, while Heinricher gives them as eight. My 
observation agrees with that of Heinricher, i. e. the number is eight. 
The resting nucleus of the macrospore-mother-cell contains a delicate 
reticulum, which may consist of a network of linin in which are embedded 
some small chromatin-granules and a large distinct nucleolus (Fig. 61). The 
reticulum then assumes a more or less thread-like structure, and gradually 
becomes located on one side of the nuclear cavity, thus entering the synapsis 
stage (Fig. 62). The synapsis stage lasts comparatively long, and is followed 
by the spireme stage. Although I was not able to find the double nature of 
the thread in the early stages of the spireme, it was more or less apparent 
in the later stages (Figs. 63, 64). The spireme then segments itself into eight 
chromosomes, each of which is bivalent in nature (Figs. 65, 66). 
The formation of the spindle now begins. The spindle is at first 
multipolar in origin, and assumes later a bipolar structure (Figs. 67, 69). 
Chromosomes then arrange themselves at the equator of the spindle. The 
number of chromosomes can easily be counted at this stage when viewed 
from a pole of the spindle (Fig. 68). Each half of the eight bivalent chromo- 
somes now travels towards the poles (Figs. 69, 70). A sign of longitudinal 
splitting is observed in the chromosomes before they reach the pole. 
As the daughter-chromosomes reach the poles their number can often 
be counted, and is always found to be eight (Fig. 71), but soon they come 
closely together until the individual outlines are lost. The nuclear mem- 
brane then appears (Fig. 72). 
The two daughter-nuclei then divide. The division is homotypic and 
.results in the formation of four granddaughter-nuclei (Fig. 73-77). 
Simultaneously with the synapsis stage of the mother-cell, the tapetal 
cells begin to disintegrate, and macrospores that have not yet separated 
from each other float in the cytoplasmic mass of the tapetal cells, as 
has already been noticed by Heinricher (Fig. 78). 
Afterwards the original wall of the macrospore-mother-cells disappears 
and the macrospores are separated from each other (Fig. 79). A single 
macrospore is surrounded by a dense mass of the cytoplasm and becomes 
enlarged very rapidly, while the rest of the macrospores move near the 
periphery of the sporangium and finally disintegrate (Figs. 80-82). So it 
can be said that the functional macrospore is nourished by the degenerating 
sister-spores and tapetal cells. 
The development of only one macrospore within each macrosporangium 
at the expense of the degenerating sister-spores and tapetal cells was 
noticed by Juranyi ( 73 ). But his description concerning the disintegration 
of tapetal cells and abortive macrospores seems to be not quite correct, 
as has been pointed out by Heinricher (’ 82 ). My observations agree on the 
whole with the statement of Heinricher. 
Although there is, as a rule, only one functional macrospore in each 
