STUDIES AMONG OUR COMMON HEPATICjE. 8j 



ation or sporophyte. Usually only one archegonium of a cluster is fertil- 

 ized, so that we have a single sporophyte developed inside each perianth . 

 ' In Lophocolea Jieteropkylla we have already studied the most im- 

 portant part of the mature sporophyte, namely, the capsule. Porella 

 platypliylla is an excellent species for studying the immature sporo- 

 phyte. If we examine a plant bearing perianths, we can easily find 

 among them some which show the opaque young sporophytes through 

 their translucent walls (Fig. 5). If we dissect out one of these struc- 

 tures (Fig. 14) carefully, we shall find that the sporophyte is still 

 tightly enclosed within a second translucent covering tipped with a 

 slender reddish projection. This covering is known as the "calyptra," 

 and it appears open at the base where we have torn it away from its 

 attachment to the rest of the gametophyte. The calyptra has devel- 

 oped from the wall of the venter of the archegonium and increases in 

 size to keep pace with the growing sporophyte. The small appendage 

 at the apex is the neck, which lias taken no part in the formation of 

 the calyptra, and is now in a shriveled-up condition. The calyptra is 

 nowhere united with the sporophyte and can easily be dissected away; 

 it assists in preventing the latter from drying up. At its base we 

 detect the shriveled-up remains of the unfertilized archegonia. In 

 examining the sporophyte, we notice at once that a part of it extends 

 downward below the line of attachment of the calyptra. This part, 

 which is rather irregular in shape, is known as the "foot;" it has 

 forced its way into the tissues of the gametophyte (somewhat as a root 

 forces its way into the soil) and absorbs from it the nutritive sub- 

 stances which the sporophyte needs for its development. The sporo- 

 phyte is in fact absolutely dependent upon the gametophyte for its 

 food, and the foot remains in contact with the latter until the capsule 

 is mature. Enclosed by the calyptra we note the young capsule, 

 borne on its very short stalk. 



When the capsule is mature (Fig. 15) its stalk elongates and 

 pushes it through the calyptra, which tears irregularly. The perianth 

 is then torn, usually into two lips, and the capsule appears just beyond 

 the mouth, where it splits and discharges its contents. The mature 

 capsule is similar to that of LopJiocolea. The valves, however, do not 

 reach quite to its base, and are often themselves deeply cleft, so that 

 the capsule seems to have more than four of them. The cells of the 

 valves, moreover, show irregular thickenings in their walls, and not 

 the peculiar ones usually found in the leafy hepatics. Spores and 

 elaters show nothing unusual, except that the latter sometimes have a 

 single spiral instead of two. 



The sexual organs and the young sporophyte described above are 

 uniform throughout nearly the whole of the Jungermanniales, and 



