I90 INTRODUCTION TO THE STUDY OF FUNGI 



Truffle, as a substitute for the genuine article (Fig. 78). Many of 

 the species possess a strong penetrating odour, which may be 

 useful in guiding animals where to search for them, but can 

 scarcely be protective. From their habit they are very diffi- 

 cult to find, and hence are regarded as more uncommon than 

 they probably are. They seem to 

 prefer a sandy soil, and are to be sought 

 near the roots of trees. Altogether not 

 more than seventy -five species are 

 known, of which no less than sixty 

 are European. A very few occur in 

 Australia, about fifteen in America, 

 one or two in Africa, and about three 

 in Asia, so that it is pre-eminently a 

 ^''i/efe^^Sr °^ European group. Whether we regard 

 them as degenerate Truliies or sub- 

 terranean puff-balls, they appear to be the link which unites 

 the Basidiomycetes to the Ascomycdes, by means of the 

 Tuberacei or genuine Trufties. In old age, when the asci are 

 dissolved, it is difficult to distinguish the species of Elaphomyccti 

 from the Hypogaci. 



In their earlier stage it is not difficult to determine the 

 character of the fructification. Then the walls of the in- 

 ternal cavities are lined with basidia or elongated cells, crowned 

 at the apex with two or four little spicules or sterigmata, at 

 the tips of which the spores are produced. When mature the 

 spores fall away, and lie free in the cavities. From the 

 number of spores that these cavities contain, the Rev. M. J. 

 Berkeley was led to infer that spores were produced consecu- 

 tively ; but there is no substantial evidence to support this 

 view, and no analogy in any other group of Basidiomycetes, so 

 that we fear the theory is untenable. 



Of the germination of the spores, the production of 

 mycelium, and gradual development of the young plant, we 

 are not aware that anything positive is known ; and the 

 Fungi themselves being of no economic value, their cultivation 

 has not been attempted. 



From the Gastromycetal Hypogaei we turn to the more 

 highly developed Tiiberacci, and here we find in most cases 



