IV. 



THE ANTHOCEROTES 123 



the world. The species that lias been most frequently studied 

 is A. Icrvis. The related A. Pcarsoni has been carefully in- 

 vestigated by the writer, and also the larger A. fiisiformis, a 

 common Calif ornian species allied to A. ptinctatiis. 



The gametophyte in all species is a dark green or yellowish 

 green fleshy thallus, branching dichotomously so that it may 

 form orbicular discs not unlike those of the Marchantiaceae in 

 shape; but owing to the rapid division of the growing point, 

 and the irregular margin of the thallus, the separate growing 

 points are not readily made out. The surface of the thallus 

 may be smooth asm A. lcEvis,ox much roughened, with ridges 

 and spines as in A. fiisiforinis. The thallus may be quite com- 

 pact, or there may be large intercellular spaces or chambers. 

 The latter are not filled with air, as in the similar chambers of 

 the Marchantiaceae, but with a soft mucilage. Here and there, 

 imbedded in the thallus, are small dark blue-green specks, 

 which a closer examination shows to be colonies of Nostoc, 

 which are invariably found in the thallus. Colourless rhizoids 

 fasten the thallus to the ground. Sometimes the yellowish 

 antheridia can be detected with the naked eye, but there is no 

 indication visible of the archegonia, which are very inconspic- 

 uous and completely sunk in the thallus, and their presence can 

 only be detected by sectioning. 



The sporophytes are relatively large and may be produced 

 in great numbers, this being especially conspicuous in A. 

 fusiforiiiis, where they may reach a length of six or seven 

 centimetres, and stand so close together that a patch of fruit- 

 ing plants looks like a tuft of fine grass. 



Both of the common Californian species, A. Pearsoni and 

 A. fusiformis are perennial. The growing point of the shoot, 

 with a certain amount of the adjacent tissue, remains alive and 

 persists through the summer, after the rest of the plant has 

 dried up. Probably the great ^amount of mucilage in the 

 thallus helps to check the loss of water, and enables the plant 

 to survive the long summer drought. 



Growth begins promptly with the first autumn rains, and 

 by mid-winter, or sometimes earlier, the reproductive organs 

 mature. The sporophyte continues to grow in length as long 

 as the thallus receives the necessary moisture. New sporog- 

 enous tissues develops at the base of the sporophyte long after 

 the first spores have been shed. With the cessation of its 



