FUNGT. 



241 



.(often early) division into several compartments, and thus become multicellular. 

 Such spores, arising from rows or masses of cells, are termed Compound or Septate 

 Spores. Each separate secondary cell of a spore of this description is usually 

 capable of germination, and may be termed a Merispore. The formation of gemmse 

 also occurs not unfrequently, individual branches of a hypha breaking up by re- 

 peated transverse division into a row of cells which are capable of germinating. 



The Mode of Life of Fungi is in all important features determined by the fact 

 that they are destitute of chlorophyll, and therefore do not assimilate, but are 

 adapted to take up the assimilated carbon-compounds of other organisms. This 

 they effect either by their mycelia absorbing from the ground the partially decom- 

 posed exuviae of animals and plants, or they grow upon or in excrementa, or 

 are parasites ; in the latter case they may attach themselves to living plants and 

 animals, penetrate their tissues, and thus kill them or contribute to their further 

 decomposition. In other cases their influence on their host is less injurious; 

 they then cause peculiar degenerations in the plants whose tissues they inhabit 

 {JEcidiiwi ElatincE causes, for example, the so-called ' witch-broom' of the silver fir, 

 De Bary in Bot. Zeitg. 1867). The parasitism of Fungi runs through all degrees to 

 the greatest extremes ^ ; some of them live entirely within the tissues of plants and 

 animals, and some are parasitic on other Fungi ^. Since, in consequence of their 

 want of chlorophyll, they do not require light for their nourishment, they may pass 

 through all stages of development in complete darkness, if the escape of the spores 

 or particular processes of growth do not require light, as is the case with truffles 

 and numerous other underground Fungi. Some, however, need it for their mor- 

 phological development, and do not fructify without its influence, while their myce- 

 lium on the other hand vegetates vigorously in the dark (as Rhizomorpha and many 

 others). 



With regard to the Proximate Principles for the construction of tissues. Fungi 

 present, without exception, the peculiarity of never forming starch ; but this is not 

 immediately connected with their want of chlorophyll, since phanerogamic parasites 

 like Cuscuta and Orobanche, although they form no chlorophyll^ yet produce 

 abundance of starch. Other substances usually occurring in large granules are also 

 rare in their cells. The lime very commonly taken up by Fungi is almost always 

 deposited on the surface of the hyphse in the form of small crystalline granules of 

 calcium oxalate. 



The walls of the hyph^ are not generally turned blue by iodine or by iodine 

 and sulphuric acid, or Schultz's solution ; yet the cases where this occurs are not 

 rare (De Bary, I.e. p. 7). The walls are usually thin, smooth, and without any 

 perceptible differentiation into layers, although this latter occurs in the spores, 

 especially the resting-spores, inasmuch as they form an exospore which is penetrated 

 by the endospore when they germinate. The asci of the Pyrenomycetes are often 



^ Compare what is said below on Lichens. 



- On heteioecism, a peculiar form of parasitism, see below under Book II. On insect-destroy- 

 ing Fungi, cf. Tulasne, I.e.; De Bary, Bot. Zeitg. 1867; Oscar Brefeld, Untersuchungen liber die 

 Entwickelung der Empu&a Musccb and E. radicans, und die durch sie verursachten Epidemieen der 

 Stubenfliegen u. Raupen. Halle 1871. 



^ [This statement requires modification ; vide infra.—ED.] 



R 



