208 STRUCTURE AND LIFE HISTORIES 
leafy-shoot, and in others the protonemata, may give rise 
to special small bodies, called gemma, which may become 
separated from the parent plant and give rise to new plants 
(Figs. 150 and 151). Gemmae will be illustrated more 
fully in the liverworts to be discussed in the next chapter. 
191. Comparison with the Fern. By comparing Sphag- 
num with a fern several points of interest are brought 
out. In the first place, we learn that, while the "fern- 
plant" with which we are familiar is a sporophyte, the 
sphagnum-plant is a gametophyte. In the second place, 
while the sporophyte of the fern is at first dependent on 
the gametophyte for its nutrition, the sporophyte soon 
becomes entirely independent, and the simply organized 
gametophyte perishes; while in sphagnum the sporo- 
phyte is the much more simply organized, and is depend- 
ent upon the gametophyte for nutrition throughout its 
entire life. In their mode of reproduction, however, the 
two plants are very similar, each producing haploid 
gametes of two sexes, male and female, that need to fuse 
in fertilization; the product of fertilization (zygote) being 
diploid, and producing a spore-bearing phase; and the 
spores, haploid again, through reduction, giving rise, 
without nuclear and cell-fusion to the haploid gameto- 
phyte. In each case, in the life-cycle, gametophyte 
alternates with sporophyte, fertilization with reduction, 
gametes with spores, haploid cells with diploid. What 
takes place in the cells between fertilization and reduc- 
tion, and between reduction and fertilization? This is one 
of the many fascinating problems in botany still awaiting 
solution. There is only one way by which the answers 
to these problems may be ascertained; namely, by accu- 
rate, persistent, painstaking observation and experiment. 
