Class ifi cation . 165 



colourlesSj and septate, frequently present in every 

 part of tlie host, occupying the intercellular spaces 

 and ramifying between the cells, or in some cases 

 piercing the walls and entering the cells. Haustoria 

 are produced by the mycelium of some species. The 

 resting-spores, or teleatospores as they are sometimes 

 called, are either formed from the ordinary mycelium 

 or from specialized branches, and are either naked or 

 enclosed in a special closed receptacle. In the genus 

 Entyloma spores are produced from all parts of the 

 vegetative mycelium ; the first indication of spore- 

 formation is the presence of spherical swellings which 

 increase in size for some time, and may be terminal or 

 intercalary ; from the protoplasm contained in these 

 swellings the spores are diiferentiated, and form their 

 own cell-wall while yet enclosed within the wall of 

 the hypha. The spores are usually produced in a 

 concatenate manner, and remain in the tissues of the 

 host, not becoming dry and powdery at maturity. In 

 some species the wall has an outer gelatinous layer 

 formed by the wall of the mother hypha, which is 

 persistent on the true wall of the spore. In the 

 genus Ustilago the spores are produced by special 

 branches, sporogenous ]iy_phw, which are very much 

 branched and produced in great numbers at definite 

 spots in the tissues of the host. These special spore- 

 producing hypha3 become cut up into isodiametric 

 portions by transverse septa, at the same time the 

 walls swell strongly and form a gelatinous membrane 

 enclosing the protoplasm, which develops into a spore 

 with its own cell-wall while yet enclosed in the 

 gellified wall of the hypha, which eventually dis- 



