Sketch of the Class Fungi. 293 



plants are put, as well in domestic economy as in medicine, but we 

 have touched on these before in the general introduction. In the 

 economy of nature, besides that they hasten the decomposition of 

 organic substances which supply the office of matrix to them, and 

 with which they unite in forming humus or vegetable sod, they 

 moreover serve to nourish a multitude of insects, worms, mollusks, 

 &c. It is believed that they help to purify the atmosphere by ab- 

 sorbing certain deleterious gases. 



I have not yet spoken of Phylleriace<z'^ , which Fries has placed in 

 an appendix at the end of the class. They have lately been con- 

 sidered as a luxuriant growth of the superficial cells of the paren- 

 chyma of leaves, the only organs indeed on which they occur. I am 

 inclined to think that such is their origin. M. Fee attributes their 

 presence to the larvae of insects, which stimulate the leaves and 

 elicit the anomalous development of elongated, coloured, frequently 

 transparent, simple or septate cells, forming a more or less dense 

 mass on living leaves, which are in consequence often deformed. 

 Nothing like spores has been discovered. The genera which com- 

 pose this tribe, of Avhich I have one or tv\'o species to describe from 

 Cuba, are Taphrina, Erineum, Septotrichum, Phyllerium. 



In this short and rapid sketch I have considered successively the 

 Fungi of the Avhole class, in their varied and gradually more compli- 

 cated forms ; and, as far as my powers and my limited space have 

 allowed, I have endeavoured to collect everj'thing new and interest- 

 ing which has been published respecting them during a period of 

 nearly fifteen years ; to unroll before the eyes of the reader, under 

 the form of a simple, though necessarily imperfect sketch, the vast 

 tablet representing the actual state of mycology under the twofold 

 relation of organography and physiology. To close this difficult 

 attempt, which I should not have ventured upon if it had not been 

 imposed by the plan adopted in this v/ork, and of whose success I 

 am not very confident, I must still add something on the chemical 

 composition of these plants, and of their reproduction, considered in 

 a general manner. 



The analyses of Vauquelin and Braconnot had caused chemists to 

 recognise and admit in these plants principles which the recent and 

 weU-kno'ttTi labours of my learned colleague JM . Payen on vegetable 

 substances have definitively erased from the catalogue of simple sub- 

 stances of organic chemistry. Thus, for instance, Fimgine, con- 

 sidered as a simple body, according to this excellent chemist, is but 

 a mixture of cellulose and fatty matter. IVI. Payen having had the 

 extreme kindness to communicate to me the result of his analyses, I 

 am able to give the following list of elementary substances which enter 

 generally into the composition of Fungi : — 1 . water ; 2. cellulose, con- 

 stituting all the solid part of the membranes of the tissue ; 3. three 

 azotous substances ; one insoluble in water ; a second soluble, co- 



* Fries, Syst. Myc. ill. p. 519. Fee, Mem. sur le groupe des Phylleriees, 

 8vo. Paris, 1831. Grev. Mon. Erin, in Ed. Phil. Join-., p. C7. Schloclit. 

 Mon. Erin, in Soc. Roy. Ratisb. 1822. Kunze, Mon. der Gait. Erin, ia 

 Myk. Heftii. p. 117, Leipz. 1326. Corda, Ic. Fung. iv. p. 1. 



