Morphology. 29 



the hymeDiam becomes crusted externally witli 

 minute, colourless masses of oxalate of lime. Now, 

 oxalate of lime is a product of metabolism, and so 

 long* as it remains in contact with the cell-sap is 

 held in solution, and in this condition is carried out 

 of the tissues through the cystidia along with the 

 water of transpiration. Once outside the tissues, the 

 water evaporates, leaving the lime in the solid con- 

 dition. In Ilymenochaete, a genus allied to Penijjhorciy 

 the very numerous, elongated cystidia have very 

 thick walls, of a dark brown colour, and remain 

 perfectly smooth, and do not appear to be concerned 

 with transpiration. In the Basidiomj/cetcs it is per- 

 fectly certain that the three organs described as con- 

 stituting the hymenium are homologous. Those 

 hyphee of the hymenophore that give origin to the 

 hymenial elements usually become branched in a 

 corymbose manner, and it is not difficult to meet with 

 such corymbs loosely compacted or even isolated in 

 the simpler types, as Corticium, Coniopliora, and 

 PGiiiphora, where the hymenium is frequently imper- 

 fectly developed. Such examples not unfrequently 

 have the terminal branches of the corymb differen- 

 tiated into basidia, paraphyses, and cystidia respec- 

 tively. 



Cystidia have not been met with in the Ascomy- 

 cetes, paraphyses on the other hand are generally 

 very numerous and homologous with the paraphyses 

 of the B asicUomjj ceteSj inasmuch as both originate from 

 the hyphae of the sporophore, but if the idea proves to 

 be correct that the asci originate from ascogenous 

 hyphie, distinct from the hyphce of the sporophore, 



