LECTURE XXIV. 



LECTURE XXill CONTINUED. NUTRITION OF FUNGI. LICHENS. 



Those parasites and saprophytes devoid of chlorophyll which have been con- 

 sidered so far, all belong to the highly organised subdivisions of the vegetable king- 

 dom ; in spite of their not inconsiderable numbers in species, they are, nevertheless, 

 in contrast to the enormous mass of normal green plants, to be regarded as rarities, 

 which only come before the eyes of the non-botanical observer exceptionally, and 

 play a very subordinate part in the economy of Nature ; they belong, however, to 

 the most various families of flowering plants, and in each small group of these 

 colourless plants we meet with pecuHar biological deviations from other nearly allied 

 but typical forms. 



Matters are quite otherwise in the case of the Fungi. We here meet with 

 a class of plants enormously rich in species, all the members of which are devoid of 

 chlorophyll, and are thus adapted to nourish themselves by parasitism, or at least 

 by making use of organic remains. The Fungi ^, in their sharply-expressed individu- 

 ality, so to speak, form an organic kingdom by themselves, to such an extent indeed 

 that up to the time of Linnseus, and indeed even in the present century, doubts have 

 been entertained as to their vegetable nature. 



The variety of the forms of Fungi is simply enormous. From the simplest Bac- 

 teria and their allies, distinctly visible only with the strongest powers of the micro- 

 scope, finely graduated transitions occur to the highly organised forms with massive 

 bodies, often more than a kilogram in weight and with well-marked differentia- 

 tion of tissues, the latter being offered us particularly by the Gasteromyces in ex- 

 tremely remarkable forms. Nevertheless, apart from a few of the very simplest 

 genera, the body of the Fungus is always constituted of the hyphas already described 

 — thin colourless threads, usually segmented by transverse septa ; these either live 

 singly for themselves, as in the Mould-fungi, or are united in large numbers and 



* Since I have been compelled several times in the text to refer to mycological facts which may 

 not be known to the reader, I here cite the most important works for consultation, i. De Bary, 

 'Morphologie und Physiologic der Pilze, Flechten und I\Iyxomycet£n' (Leipzig, 1864). 2. De Bary 

 and Woronin, 'Beiträge zur Morphologie und Physiologie der Pilze' R. I-IV. 3. Luerssen, ' Medi- 

 cinisch-pharinaccutische Botanik oder Handbuch der system. Bot.' B. I (Leipzig, 1874). 4. Goebel's 

 new edition of the systematic portion of my ' Lehrh. der Bot' (Leipzig, 18S2). 5. Frank, 'Die 

 Krankheiten der Pßanzcn' (Breslau, iSSoj. 



