470 CLASS BASIDIOMYCETEAE 



the first spindle. Such basidia are called chiastobasidial. It was shown 

 that many of the Thelephoraceae and Clavariaceae and some of the 

 genera hitherto placed in the Agaricaceae were stichobasidial while most 

 of the Polyporaceae and Agaricaceae and Boletaceae were chiastobasidial. 



As more and more species and genera of the Hymenomycetes became 

 known it was necessary to find other characters for their classification 

 than the external morphological ones which largely formed the bases 

 for the studies by Fries. The form and color and surface characters of the 

 spores showed their importance, but soon the anatomy of the spore fruit 

 and especially of the trama, the tissue upon which the hymenium is pro- 

 duced, proved to be of great value, as well as the mode of development of 

 the spore fruit. The old families had to be broken up and recombined in 

 order that a more logical systematic treatment could be expressed. 

 Patouillard (1900) recognized two main groups: "Aphyllophoracees," 

 with the hymenium naked from the first and capable of continued ex- 

 pansion, and "Agaricacees" with the hymenium more or less lamellar 

 and hemiangiocarpic, i.e., at first enclosed by a more or less fugacious veil 

 which is variously ruptured at maturity. Later authors have called these 

 Polyporales and Agaricales respectively. The old families Boletaceae and 

 Agaricaceae made up the latter order, the Polyporales containing the 

 other Friesian families and one or two stichobasidial genera from the old 

 family Agaricaceae (e.g., Cantharellus) . In the main the Agaricales as so 

 delimited were chiastobasidial, but the Polyporales had both types of 

 basidia. This led Gaumann (1926) and others to divide the included 

 families into two series, stichobasidial and chiastobasidial. The fact that 

 in the same hymenium of Exohasidium both types may occur throws 

 doubt upon the validity of this as a fundamental character, although it is 

 apparently correlated sufficiently with other characters to make it 

 important. 



Another character has been emphasized recently as of perhaps great 

 importance: the blue or violet coloration of the basidiospore exospore or 

 of the warts or network of lines on the spores upon treatment with a solu- 

 tion containing free iodine. In some cases even certain of the hyphae of the 

 spore fruit give the same reaction. Such spores and hyphae are said to be 

 amyloid (i.e., starch-like in their reaction). Just how far this can be used 

 in revising the arrangement of genera and families is uncertain for within 

 certain genera (e.g., Mycena) occur some species with amyloid and some 

 with non-amyloid spores. 



Although the presence of clamp connections on the mycelium is well 

 known in a great many of the Hymenomycetes yet it has been found that 

 they may be absent in some genera on the hyphae in the interior of the 

 spore fruit. This has been used as a supplementary generic character but 

 cannot be considered as of fundamental importance. In the genus Coprinus 



