166 RESEARCHES ON FUNGI 



of Coleosporium, in being straight, transversely septate, and four- 

 celled, and in having lateral sterigmata which pierce through 

 mucilage derived from the walls of the basidia, are practically 

 identical in their nature with those of Auricularia. There can be 

 little doubt that the close resemblance of the basidia of the Ure- 

 dineae and of the Auricularieae is based upon inheritance from a 

 common ancestor. The septa in the long cylindrical basidia of the 

 Auricularieae strengthen the basidia mechanically, and also serve 

 to separate from one another the four masses of protoplasm which 

 are destined to pass up the widely separated mouths of the sterig- 

 mata into the four spores. After separation from one another 

 by the intervening septa, the four masses of protoplasm act as 

 independent morphological and physiological units. This I take 

 to be advantageous so far as spore-formation is concerned, owing 

 to the distance of the mouths of the sterigmata from one another. 

 It is probably simpler and easier for a long cylindrical basidium 

 with lateral sterigmata to supply the proper amount of proto- 

 plasm to each of its four spores when it is septate than when it is 

 non-septate. 



In the Tremelleae, the basidia are more or less globular and 

 are divided into four cells by two walls which cross one another 

 at right angles through the basidium-axis. 1 Each of the four 

 cells has a long arm or sterigma which pierces through the gelatin- 

 ous matrix and comes to project into the air. By means of the 

 crossing walls, the contents of each basidium, just as in the Auricu- 

 larieae, are divided into four morphological and physiological 

 units. Probably this division, especially since the basidium-body 

 is globose, simplifies the work of supplying the proper amount of 

 protoplasm to each spore. Now the non-tremelloid Hymenomy- 

 cetes, e.g. the Agaricineae, have basidia which are clavate instead 

 of globular and non-septate instead of septate, and which bear at 

 their free ends four closely approximated relatively small sterig- 

 mata. No doubt the building of cross-walls in a basidium only 

 takes place with the sacrifice of physiological energy and time as 

 well as of organic substance. I therefore regard the basidia of 



1 It is possible that the septa in some species are not complete and that the four 

 cells of the basidium open below into a common cavity. 



