MM. Tulasne on the History of the Hypogaous Fungi. 21 



free extremity three or four spores, becoming successively de- 

 tached, and finally filling the cavities. 



The other type, comprising the true Truffles and forming the 

 groups TuberacecB and Elaphomycea, also present a fleshy mass, 

 the outer surface of which constitutes the common envelope or 

 peridium, while the numerous narrow, sinuous, not very distinct 

 cavities are lined and in part filled up by a special tissue, mingled 

 with cells of a peculiar form, producing in their interior three or 

 four or from six to eight spores, like the thecse of the Pezizea. 



Thus in the hypogaeous as in the ordinary Fungi, there are two 

 different modes of formation of the spores ; in the one class these 

 reproductive bodies are developed upon the external surface of 

 special cells called basidia or sporophores ; in the other they are 

 formed in the interior of particular cells named thecce or spo- 

 rangia. 



This difference in the mode of production of the spores had 

 already been shown by M. Vittadini's observations and figures, 

 although he sought to explain it by an accessory modification of a 

 single kind of organization. It was established in a much more 

 positive manner in different groups of Fungi by various authors 

 of more recent date, by Messrs. Leveille, Klotsch, Berkeley, and 

 Messrs. Tulasne themselves in various memoirs. It now forms 

 the basis of the divisions both of the hypogseous and of the ordi- 

 nary Fungi. 



But many essential points in the very obscure life of these 

 strange plants still remained to be elucidated. 



The discovery of numerous species, the comparison of their 

 form, of their organization, their distribution into well-defined 

 genera, in a word, the natural history properly so called of this 

 curious subterranean flora, has not only resulted in increasing 

 the catalogue of organisms of this kind ; these discoveries have, in 

 addition, allowed of a better appreciation being arrived at of their 

 mode of existence, development and reproduction ; for this diver- 

 sity of organization has yielded the solution of questions which 

 would have been very difficult to answer from the study of a 

 small number of species. How many physiological questions 

 have been cleared up in this way by the examination of varied 

 forms of the inferior members of the scale of organization ! 



The well-directed investigations of Messrs. Tulasne, in the 

 neighbourhood of Paris and in different parts of France, have, in 

 the first place, enabled them to extend the list of these plants 

 greatly; thus, while M. Vittadini, in 1831, indicated only sixty- 

 three species, distributed into thirteen genera, Messrs. Tulasne 

 have carried the number to a hundred and forty-four species 

 comprehended in twenty-five genera, and have added seventy- 

 one of these species to the French flora. 



