200 THE PHENOMENON OF 



granules ; also in Ulothrix, where the cells contain about 

 six, and in Ascidium arid Pediastrum, where the cells have 

 only a single starch-grain. In Chlamidococcm the starch- 

 grains vanish at the commencement of the division of the 

 active cells (to be described hereafter). 



The formation of fixed oil is intimately connected with 

 that of starch in the economy of cell-life ; its appearance, 

 in like manner, announces the repose of age in cell-life, 

 its disappearance the beginning of Rejuvenescence. We 

 meet with fixed oil in the cells, either mixed with starch, 

 substituted for it, or gradually displacing it ; its occur- 

 rence is perhaps still more general than that of starch, 

 since it exists even in the Fungi and Phycochromiferous 

 Algae. Like starch, it is met with in greatest abundance 

 in those parts in which vegetation is destined to rest and 

 to await a future re-awakening, for instance, in tuberous 

 stolons (Cyperus esculentus) and rhizomes (Isoetes,* Aspi- 

 dium Filix mas.} ; in the seeds of the Phanerogamia, 

 either in the albumen (Euphorbia, Umbelliferae, Vitis], 

 or in the embryo (Crucifera3, Compositae, Cucurbitaceae, 

 Amygdaleae, Juglandese) ; in the resting spores of Ferns, 

 Lycopodiaeeae, Mosses,t Hepaticae, j Lichens, and many 



* Especially in the terrestrial species : /. hystrix, Durieu ; and /. duritei, 

 Bory, ('Explor. Scient. d' Algeria,' Bot., t. xxxvi), as also those which 

 grow on spots only overflowed in winter, as /. setacea, Bosc., 7. adspersa, 

 A. Braun, 7. velata, A. Br., (ibid., t. xxxvii). All these contain only a little 

 starch but a great abundance of fixed oil, in the short tuberous stem, while 

 our always aquatic /. lacmtris exhibits but little oil with abundance of 

 starch. The oleaginous Isoetes all have the power of surviving a long time 

 in a perfectly dry condition. 7. hystrix and Durieei grow upon the dryest 

 hills of Algeria, in loose sand, close to the surface of the ground, where they 

 are exposed during eight or nine mouths to the greatest drought and the 

 most burning heat of the sun. According to the experience of Durieu, the 

 tubers of these species still remain alive, after having been kept dried for 

 five or six years ; I myself have seen a specimen of Isoetes setacea revive and 

 vegetate after it had lain almost two years in an herbarium. 



f According to W. Schimper, ('Recherch. sur les Mousses,' p. 77), the 

 contents of the spores of Mosses are oily, without a trace of starch. 



J According to Mohl, ('Verm. Schrilt.,' pp. 87, 90), the developing spores 

 of Anthoceros contain starch-grains, while the ripe spores contain only a 

 mucilaginous fluid in which oil-drops are intermixed. 



The spores of the Lichens (Mohl, ' Verm. Schrift,' p. 75) often contain 

 an oil-drop. 



