No, I1.] THE BRYOPHYTES OF CONNECTICUT. II 
sporophyte which remains in close contact with the gameto- 
phyte usually forms a special absorbing organ, or foot. This 
organ, however, never acquires the power of absorbing from 
the outside, so that the sporophyte is never able to exist as 
an entirely independent plant. 
The spores are borne within a closed case, or capsule, 
which constitutes the so-called fruit in the Bryophytes. The 
capsule is bounded on the outside by a sterile wall, and the 
space in which the spores are developed is known as the 
Spore cavity. When the spores are mature, they lie loose 
within the cavity, and are set free by the rupturing of the 
wall. In the majority of cases the capsule is borne on a 
slender cylindrical stalk, which connects it with the foot and 
at the same time lifts it above the gametophyte. 
When the fertilized egg begins to divide, the sterile cells 
which form the wall of the venter also undergo divisions and 
develop into a protective covering for the young sporophyte. 
This covering is called the calyptra, and for a considerable 
period its growth keeps pace with that of the sporophyte. 
Sooner or later, however, it ceases to enlarge and is eventually 
ruptured by the swelling capsule. The neck of the fertilized 
archegonium plays no part in the development of the calyptra, 
but can frequently be detected at its apex in a shriveled condi- 
tion. In a few specialized genera a true calyptra is not formed. 
Upon germination a spore at first gives rise to an embryonic 
structure, or protonema, upon which the characteristic gameto- 
phyte afterwards develops. The protonema is sometimes 
very short-lived, but in many species persists for a considerable 
period. It usually consists of a copiously branched filamentous 
structure, but it may be composed of a flat layer of cells or 
of a small solid cell mass. In some cases the protonema is 
represented by a very few cells arranged in a simple cell row 
and is then scarcely distinguishable. 
Although very few Bryophytes are truly aquatic, it has 
been shown that the presence of water is necessary for the 
process of fertilization. It not only enables the antheridia and 
archegonia to open, but it also affords a medium in which 
the motile sperms can swim. The water is usually supplied 
by rain, but, if no rain falls at the proper time, the antheridia 
and archegonia gradually shrivel. away and sporophytes fail to 
