68 
NATURE STUDY. 
tutes a very remarkable connecting link between the other two. 
I will endeavor to state briefly the most important fact bearing 
upon the interrelations of these families. 
When a fern sets out to reproduce itself it concentrates its 
energy in certain cells, transforming the matter in them from 
mere vegetative to reproductive substance. These cells event¬ 
ually become filled with spores, i. e., they become sporangia or 
spore-cases, and the spores when ripe are set free to give rise to 
the intermediate generation fprothallium) from which the next 
generation of spore-bearing plants will grow. Now the choice 
of cells in which the initial process of reproduction takes place 
is the chief distinguishing characteristic of the families. In the 
first family, which is of very ancient origin and closest to the 
archaic type, the sporangia are formed of cells in the interior 
tissue of the leaf, or hypodermal cells; in the third family they 
are formed of cells in the exterior tissue, or epidermal cells, 
while in the second family they are formed partly of the interior 
and partly of the exterior tissue. In ordinary language we 
might say, for example, in Botrychium the spores are formed in 
the flesh of the plant, in Osmunda partly in the flesh and partly 
in the skin, and in Polypodium and the rest in the skin only. 
Our common Osmundas are thus seen to occupy a very inter¬ 
esting and important place in the evolutionary scheme of ferns 
and to form a transitional group between the most ancient and 
most modern groups at present kuown. A further treatment of 
their specific characters must be deferred to a future article. 
Intuition. 
BY HENRY CLEVELAND WOOD. 
How does it know — this tiny hidden thing — 
Within its wilderness of tangled grass, 
The hour when Summer’s languid footsteps pass, 
And Southward-flying birds are on the wing, 
While earth is dumb with August’s silencing ? 
How does it know the time for purplish haze, 
Or guess the wondrous transformation scene, 
Which sets the fields and forests all ablaze ? 
Yet, in shrill notes, from drowsy ways of green, 
Breaking the spell that passing Summer sways, 
The cricket first proclaims the Autumn days. — Ainslee’s Magazine 
