Page:An introduction to physiological and systematical botany (1st edition).djvu/521

 Rh in this branch of physiology. He examined all that had been done before his time, detected the truth, raised mosses from seed, and established their characters on the principles we have already explained.

The Linnæan genera of Mosses are chiefly founded on the situation of the capsule, whether lateral or terminal, with some other circumstances. They are too few, and not strictly natural. Hedwig first brought into notice the structure of the fringe, peristomium, which in most mosses borders the orifice of the capsule. This is either simple or double, and consists either of separate teeth, or of a plaited and jagged membrane. The external fringe is mostly of the former kind, the inner, when present, of the latter. The number of teeth, remarkably constant in each genus and species, is either 4, 8, 16, 32 or 64. On these therefore Hedwig and his followers have placed great dependance, only perhaps going into too great refinements relative to the internal fringe, which is more difficult to examine, and less certain, than the outer. Their great error