26 
a@ mere granule consisting of a single cell with a double membranous 
coat, containing no embryo, and, therefore, no plumule, radicle or 
cotyledons. Germination takes place from any part of it, and, in 
many cases, the body produced is not the future plant growing 
above ground but only a stage in the life-history of the plant 
—Moss or Fern as the case may be. When a Fern spore 
germinates it produces a flat leaf-like body called a prothallus, 
on which are formed antheridia and pistillidia, organs serving 
the same kind of purpose as the stamens and pistils of ordinary 
flowers. After fertilization has taken place, resulting in the 
production of a young fern, the prothallus, having served its pur- 
pose, withers away. When a moss spore germinates, a green mass 
of jointed threads called a protonema is produced, and from this 
there arise shoots that grow into moss plants, the protonema, 
except in afew cases, withering away (in the Ephermere, plants of 
rapid growth, the protonema is persistent during the life of the 
plant). It must be noticed that the fern spore gives rise not to the 
plant we call a fern, but to a prothallus which is called the /irst 
generation or sexual generation or oophore. The fern, as we see 
it above ground, does not bear autheridia and pistillidea but only 
spores. It is, therefore, called the second generation, the asexual 
generation or sporophore. Alternation of generations in mosses 
occurs in a different manner. First there is the spore, then the 
protonema, then the above-ground moss which is also the sexual 
generation or oophore. This generation, by means of its antheridia 
and pistillidia, brings about the asexual or second generation or 
sporophore which is none other than the capsule. Here, then, is 
the cycle of moss-life—spore, protonema, moss-plant, spore, over and 
over and over again. Alternating generations, are not confined to the 
Vegetable Kingdom but are very familiar to students of Zoology, 
for instance in the life-history of ajelly fish. The leaf of a moss 
which is always sessile, isa very important part of the plant, not 
only for obvious reasons but also because its structure 
has a great deal to do with classification. The field botanist re- 
members all about net-veined, parallel and forked venation, but 
does not need to know much about the details of leaf strueture in 
order to refer a plant—say a Buttercup—to its natural order, but 
the student of mosses has, again and again, to use his magnifier 
(and his ‘ binocular’ too) in examining the leaf and trying to make 
out what is characteristic in its structure. The areolation, as it is 
called, is important in all mosses, but especially so in the case of 
those that never bears fruit. When examining such a moss, the 
student has to carefully note its habit and then look to the leaf to 
be his guide. It used to be thought that the peristome was, so to 
speak, everything, but now the cell-structure of the leaf is known to 
