83 



like the other Hverworts, rc\L;iihirl)' survive the summer in a dor- 

 mant state. A former erroneous statement (" Mosses and Ferns," 

 p. I 17) tliat they are annuals, was due to a failure to examine 

 the plants early enough in the season. 



Maving observed how soon after the first rains mature repro- 

 ductive organs were present, it was thought advisable to investi- 

 gate the condition in which the plants pass the dry season. The 

 matter was intrusted to one of our students, Mr. H. B. Hum- 

 phrey, who has made a careful examination oi Fossombronia lon- 

 giscta and Fimbriaria Calif arnica {Aster clla Californicd), as Ave 11 

 as a less complete examination of a number of other species. 



It was found that a surprisingly large amount of the thallus 

 remains alive, and within a few hours after the dried plants are 

 supplied with water, the forward part of the thallus has assumed 

 its active condition and begins to grow. In both Fossombronia 

 and Fimbriaria {Asterelld) the first antheridia were mature in 

 about two weeks. This early development of the reproductive 

 organs at once raised the question whether they might not begin 

 their development before the close of the growing period in the 

 spring. To determine this point, dried plants were collected and 

 placed in water and were examined as soon as they had revived. 

 In Fossombronia both archegonia and antheridia were found in 

 advanced stages of development, while in the dioecious Fimbriaria 

 {Astarlla) the male plants showed large antheridia, but the female 

 plants had not yet formed archegonia. It is highly probable that 

 the reproductive organs are present also in all the species o( Riccia, 

 and not unlikely in some of the other genera, but as yet none of 

 these have been critically examined for this point. 



That the liverworts can endure much greater desiccation than 

 that to v.'hich they are normally subjected was shown by remov- 

 ing by artificial means a large part of the water held in the dried 

 thallus. The plants so treated showed no apparent loss of 

 vitality, and promptl}' revived when supplied with water. 



In all the forms examined, more or less perfect devices for pre- 

 venting excessive loss of water have been noted. The growing 

 point is protected by hairs or scales, sometimes secreting mucil- 

 age, and the mucilage cells within the thallus of certain species 



