384 EIBLIOGRAPITY. 



axis, as may be observed in Bartramia Halleriana Hedw. and in 

 many Dicrana. 



3. By observing the number of shoots, where several are 

 united together, and form what the author calls a Sympodium. 

 Some mosses produce horizontal subterranean runners, which 

 eventually appear above ground, and produce leaves and fruit. 

 At the point where each runner bends upwards, a bud is deve- 

 loped in the axil of a leaf. This bud forms a second subterranean 

 runner, and at last appears above ground like the former one. 

 This process is repeated yearly, so that by counting the number 

 of shoots which appear above ground, the age of the moss is ar- 

 rived at. Minum unduiatum Hedw., Climacium dendroides W. 

 and M., and Thamnium alopecurum Schpr. may be examined in 

 this way. 



4. This method applies to Polytrichum only, and depends 

 upon the fact of the growth of the stem in that genus being 

 carried on through the inflorescence. 



5. The 5th method (an uncertain one) is by observation on the 

 size of the leaves. The early spring leaves are the smallest, and 

 those produced as the year advances become gradually larger and 

 larger. "With the following spring the small-sized leaves reappear. 

 Thus each point of commencement of the small-sized leaves marks 

 the commencement of a year. In Leucobryum and in many 

 Dicrana this plan may be used. 



In the pleurocarpous mosses, the fruit not being terminal, the 

 growth of the principal axis is not limited, and it is in most cases 

 not possible to fix the age of the stem. An exceptional case 

 exists in Ili/locomium splendens Schpr. where new axes of growth 

 are formed at regular intervals. 



The age of moss stems determined in this manner is found to 

 vary between 3 and 10 years, but this does not represent the 

 duration of the whole period of vegetation of a moss. As the moss 

 grows, the older portions of the stem decay by degrees, and in 

 order to determine the length of the whole period of vegetation, 

 it is necessary to examine instances where the decay is arrested. 

 This may be done in the case of Sphagnum where the old portions 

 have formed peat, or where, as sometimes happens, the lower 

 parts of a moss have become incrusted with carbonate of lime. 



We have not space to go into the details of the author's re- 

 marks upon this part of the subject, but he arrives at the con- 

 clusion that mosses attain an age equal to that of the oldest trees. 

 Eoze, Ernest, and E. Bescherelle. — Note sur quelques Mousses 

 rares ou nouvelles, recemment trouvees aux moirons de Paris. 

 Bull. Soc. Bot. vii. pp. 433-4. 



3. Lichens. 

 Massalongo. — Catagraphia nonnullarum Graphidearum Brasilien- 



