74 ERYTHEA. 



as bearing upon the problem of the relative position of these 

 two great groups of liverworts. 



The ripe spores of our species are nearly globular, about 

 65-70yu in diameter. The nearly black exospore is marked 

 with very distinct reticulately anastomosing ridges. In num- 

 erous specimens, collected from various localities near Stan- 

 ford University, the spores were almost always quite separate 

 at maturity, although in all the published descriptions of 

 Sphserocarpus that I have examined, the spores are described 

 as being permanently united in tetrads. Professor L. M. 

 Underwood writes me, however, that he has also observed the 

 separation of the ripe spores. As is well known, no perfect 

 elaters are present, but the oval sterile cells which are 

 mingled with the spores, no doubt are the homologues of the 

 elaters of the more specialized liverworts. 



The germination of the spores corresponds closely to that 

 of Eiccia,* especially in the formation of a very long germ- 

 tube which is almost always present. The ripe spores con- 

 tain no chlorophyll and owing to the opacity of the exospore 

 it is difficult to see clearly the character of the contents be- 

 yond the fact that they are dense and opaque. The spores 

 probably require a period of rest before germinating, but 

 this was not tested. Those collected as soon as they were 

 ripe, about the middle of May, germinated freely in the 

 autumn and winter, but the later sown spores did not seem 

 to germinate quite so promptly, although no exact record was 

 kept. The first signs of growth are usually evident within a 

 week or less after the spores are sown. The exospore is rup- 

 tured and through the cleft the ^ndospore protrudes as a 

 slender papilla which rapidly elongates until it forms a 

 slender filament, or germ-tube, of considerable length. At 

 first its contents are opaque, owing to the granular matter 

 and small oil drops present; but as it lengthens these are 

 carried out to the end leaving the basal portion almost desti- 

 tute of granular contents and quite colorless. Only a few 

 chloroplasts are evident at first, but these soon enlarge and 



4 Campbell, Mosses and Ferus, p. 37. 



