DICHOCARPISM 65 



the substance. Upon this mycelium erect branches are 

 developed and form conidiophores, having the habit and 

 appearance of an ordinary mould. The conidiophores branch 

 several times ; the branches, usually three, form a whorl, and 

 these again are similarly branched in whorls, the branchlets 

 being each terminated by three shorter branchlets in a whorl, 

 each branch and branchlet being attenuated upwards. The 

 terminal branchlets bear one or more small oval conidia. This 

 has been called Verticillium micro&permum. Upon the same 

 mycelium grow a number of ovate perithecia, which are clad 

 with a dense short wood ; and when mature they contain 

 numerous asci, each enclosing eight lanceolate uniseptate 

 sporidia. This is Hypomyces broomeanus, of which the above 

 mould bears the conidia. Hence this species is dichocarpous, 

 one form of fruit being the mould, and called the conidia, the 

 other the Sphaeriaceous Ascomycete with asci and sporidia. 



Maple leaves will furnish another example in the well- 

 known pitchy blotches which are so common in autumn as 

 to attract every eye. These black patches, which are closely 

 adnate to the leaves, are the stroma of Melasmia acerina, as 

 it is then called. The perithecia are cells immersed in this 

 stroma, which contain small hyaline curved sporules borne on 

 short slender sporophores. After these leaves have fallen on 

 the ground and lie in damp places during the winter, another 

 form of fruit is developed within the same stroma ; but in this 

 instance the sporidia are developed in asci and are nearly ten 

 times as long as the sporules, thread -like and flexuous. The 

 stroma itself becomes more corrugated, and splits irregularly to 

 allow the sporidia to escape. In this state it is called Rhytisma 

 acerinum, but the two forms are one species, with a stylosporous. 

 and an ascigerous form of fruit, and the latter is never matured 

 until the leaves have lain for some time upon the ground. 



We may select the living leaves of the hedge maple to 

 furnish our next example, which can be found in summer in 

 any hedgerow. At this time the leaves are covered or blotched 

 with white, as if they were whitewashed, but seen under a 

 microscope this appearance is caused by a dense mycelium of 

 white threads adhering to the surface of the leaf. From these 

 threads arise short erect branches, which become' constricted 



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