[Vol. 2 



672 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



Spore characters. — Spore characters are probably worthy 

 of a great deal more consideration than they have yet received 

 in the greater part of the mycological work that has been done 

 up to the present time. As previously stated, in the Agari- 

 caceae the primary divisions of the family are made on the 

 basis of spore colors. This distinction was made as early as 

 1821 by Fries in his 'Systema Mycologicum. ' The fact that 

 ihis oh ar Afrt.er was so earlv recognized was not because spores 



more abundant or their colors more strikin 



g in nic 6 



fungi, but because the period of spore production more 

 closely coincides with the period of maximum development of 

 the plants. Unfavorable conditions, i. e., drought, super- 

 abundance of moisture, cold, etc., result in the disorganiza- 

 tion of the tissue in a fleshy fungus, and consequently the 

 duration of the period of spore liberation is permanently 

 shortened. In the coriaceous or woody forms these same con- 

 ditions result only in a temporary suspension of the act of 

 spore liberation and with the return of normal conditions the 

 suspended function again becomes active. In this way the 

 period during which spores are present in the hymenium of 

 a pore fungus is greatly lengthened, and it is safe to assume 

 that the number of mature spores present at a given time in 

 the hymenium of one of the more durable pore fungi is less 

 than the number of mature spores on an equal hymenial sur- 

 face of a gill fungus. Contrary to the condition in the 

 Agaricaceae, the introduction of spore colors as generic char- 

 acteristics would mean an entire revision of all the genera, 

 and it may well be doubted whether the advantage obtained 

 from such a limitation of genera would compensate for the 

 confusion that would be sure to arise. On this basis, how- 

 ever, the species could easily be grouped into sections under 

 the genera, but even were that done the white-spored species 

 so far outnumber those with colored spores that the adoption 

 of the idea would delimit only a small group of species that 

 perhaps could be better separated in other ways. 



Very little exact evidence bearing on the variation in size 

 in the snores of a given species is obtainable. The work of 



