DESICCATION 255 



of many Osmundaceae, Hymenophyllaceae *, and of Equisetum z , however, rapidly 

 die when kept. 



Mosses. Schroder found that the most resistant mosses died in the course 

 of a few years 3 , and the power of dead mosses of becoming apparently fresh when 

 moistened, has led some authors to conclude that they were still living after 

 remaining for a hundred years in a herbarium. The perennating parts of the 

 protonema seem to live for a longer time, and the spores have in part retained 

 their vitality for as long as fifty years 4 . Most Hepaticae 5 , in correspondence with 

 their moister habitats, are less resistant than mosses, but those forms which live 

 in dry places remain living for a longer or shorter time in the dried condition. 

 For example, Corsinia marchantioides was found to be still living after remaining 

 for nine months in a herbarium. 



Algae 6 . The zygotes and other resting spores of fresh-water algae can usually 

 withstand desiccation, and the vegetative cells of such forms as Cystococcus hutnicola, 

 Pleurococcus^ and Scenedesmus, which grow on moist soil, possess the same power. 

 Some species of Nostoc and Oscillaria can withstand a short period of desiccation, 

 others a long period. Diatoms are killed by complete but not by partial drying in 

 air. Many lichens are resistant to a high degree 7 , and it is interesting to notice 

 that the algal components appear to be more resistant in the form of a lichen than 

 when free 8 . 



Fungi 9 . The mycelia of most fungi, including mould fungi, are killed by 

 drying, whereas the spores, sclerotia, and other perennating organs are usually highly 

 resistant. All grades of transition are, however, shown between organs resisting 

 drying for a few days, and those which remain living for years. The spores 

 (conidia) of Aspergillus fumigatus may remain living for as long as ten years, 

 whereas the spores of moulds usually do not germinate after one to three years, 

 and those of the more resistant Ustilagineae after eight to nine years. The spores 

 and sclerotia of Myxomycetes 10 also withstand drying, but appear usually to die 

 after from six to twelve months. The vegetative cells of species of Saaharomyces 

 can withstand drying over sulphuric acid u , and Will found them still living after 

 being kept dry in air for thirteen years. 



Bacteria. The vegetative cells show all grades of resistance, whereas the 



p. 132 ; Schimper, Bot. Mittheil. a. d. Tropen, 1888, Heft 2, p. 36 ; Heinricher, Ber. d. Bot. Ges., 

 1896, p. 234 (the adventitious buds of Cystopteris bulbifera). 



I Sadebeck, Schenk's Handbuch d. Bot., 179, Bd. i, p. 156. 

 * Buchtien, Bibl. hot., 1887, Heft 8, p. 15. 



3 Cf. Schroder, Unters. a. d. Bot Inst. zu Tubingen, 1886, Bd. II, p. 15. 



4 Schimper, Rech. anatom. et morphol. s. 1. mousses, 1848, p. 22. 



5 Cf. Schroder, 1. c., p. 14. See also Goebel, Pflanzenbiol. Schilderungen, 1889, I, p. 174. 



6 Cf Schroder, 1. c., p. 21. 7 Schroder, 1. c., p. 38. 



8 Ewart, Linn. Soc. Trans., 1896, Vol. xxxi, pp. 382, 383. 



9 Schroder, 1. c., p. 34; de Bary, Morphol. u. Biol. d. Pilze, 1884, p. 368 ; Zopf, Pilze, 1890, 

 p. 317; Wehmer, Centralbl. f. Bact., 1895, 2. Abth., Bd. I, p. 217; Eriksson, ibid., 1894, 2. Abth., 

 Bd. iv, p. 431. 



10 Schroder, 1. c., p. 36; de Bary, 1. c., p. 483. 



II Schroder, 1. c., p. 37 ; Will, Centralbl. f. Bact, 1900, 2. Abth., Bd. vi, p. 226. 



12 De Bary, Pilze, 1884, p. 515; Fliigge, Mikroorganismen, 1896, 3. Aufl., Bd. I, p. 415; 

 Ficker, Ueber Lebensdauer u. Absterben von pathogenen Keimen, 1898. 



