ijd THE PLANT WORLD. 



the lower part it is circular in section, btit above the middle it is 

 triangular, and is therefore in the form of a three-faced prism ; if the 

 perianth is pressed backward, the prism is found to lie in such a way 

 that one of its faces is parallel to the ground, while the other two 

 meet in a sharp angle or " keel " above. At the mouth, which is not 

 at all contracted, the perianth is deeply three-lobed, the lobes being 

 continuous with the three faces of the prism. The lobes themselves 

 are more or less distinctly bilobed and are in addition coarsely and 

 irregularly toothed. The perianth is looked upon as an organ formed 

 by the coalescence of modified leaves, just as a gamopetalous corolla 

 is formed by the coalescence of petals. Three such leaves take part 

 in the formation of a perianth, an under leaf and two side-leaves; and 

 the three ilat faces of the prismatic perianth of LopJwcolea correspond 

 with these three leaves, the face parallel to the ground representing 

 the underleaf, and the other two, which meet in the keel above, the 

 side-leaves. This formation, which is so clearly evident in Lophocolea., 

 is made obscure in Jnngermaimia barbata from the fact that the three 

 angles have become indistinct and that the mouth of the perianth is 

 contracted and shows no distinct lobes. 



LopJiocolca heterophylla "fruits" so frequently that we may use 

 it for the study of the most characteristic part of the sporophyte, 

 namely, the "capsule," If we gather a tuft of our plants covered 

 with perianths in early spring and place it in a saucer underneath 

 a tumbler, where it must be kept moist but not wet, we shall proba- 

 bly be able to note the appearance of these interesting structures 

 in the course of a week or two. Out of doors, the capsule is not 

 usually mature until May. It first shows itself at the mouth of the 

 perianth as a glossy, oval body, dark brown or almost black in color. 

 Very soon it is carried high above the perianth by the rapid elonga- 

 tion of its stalk. The latter is extremely delicate in structure and 

 has a white translucent appearance ; its growth is brought about by 

 the elongation of its cells and not by the formation of new ones, and 

 it sometimes attains a height of several centimeters in a few hours. 

 After a while or very quickly, if the plants are exposed to a dry air, the 

 wall of the capsule splits longitudinally down to its attachment with 

 the stalk into four equal "valves" and the contents are discharged; 

 soon afterwards, what is left of the capsule with its delicate stalk 

 shrivels up and disappears. 



The valves thin out on their edges into a single layer of cells, but 

 in the middle they are two or more cells thick. The cells are char- 

 acterized by peculiar local thickenings in their walls. In all except 

 those of the innermost layer, the thickenings are in the form of scat- 

 tered opaque ridges on the partition walls of the cells and appear in 



