ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 265 



and a height of 0*5 mm. From the middle projects a yellow 

 columnar body, about 2 mm. in height, composed of a number of 

 vertical filiform bodies rising from its base, the space between them 

 being completely filled by a mass of yellow spores. The fructification 

 may be regarded as consisting of four parts, an outer peridium, an 

 inner peridium, a spore-forming layer, and a tuft of hyphse. 



The outer peridium consists of a circular wall which spreads over 

 the epidermis of the leaf of the host ; it varies greatly in thickness, 

 and consists of a number of branched hyphse. This is bounded on the 

 inside by a very delicate membrane, the inner peridium. 



The hyphae which are destined to the formation of spores spring 

 from the central part of the peridium ; they are vertical to the surface 

 of the leaf, and form a continuous palisade-like layer. The ends of 

 these hyphfe are thicker than those of the hyphse which compose the 

 sterile weft ; they increase gradually in diameter upwards, attaining 

 at the apex a thickness of about 3-4 fx. They are colourless, and 

 filled with protoplasm which is either homogeneous or more refringent 

 in some parts than others ; they are septated tranversely into short 

 cells, which at length swell into a spherical or ellipsoidal shape 

 and become readily detached from one another. On the upper of 

 these cells small protuberances now make their appearance, which 

 gradually increase in size till they have attained that of the cells 

 from which they spring ; from three to six of them springing from one 

 of the cells of the hyphas. They are thin-walled and filled with pro- 

 toplasm of varying refrangibility, which has passed into them from 

 that of the hyphal cell, which eventually perishes. These bodies, 

 which the author calls " spore-initials," produce the spores by one or 

 more bipartitions of their contents. The ripe spores are usually found 

 connected together in pairs ; they are spherical or ellipsoidal, and 

 about the same size as the initials, 3-6 fx in diameter ; their mem- 

 brane is usually moderately thick, colourless, and smooth. 



The tufts of sterile hyphte spring, like the fertile ones, from the 

 bottom of the fructification. They are slender, cylindrical, or irregu- 

 larly prismatic bodies, from 7-18 /x in thickness, and strongly 

 refringent. Each larger bundle consists of from 50 to 100 of such 

 hyphse ; their membrane is much thicker and more refringent than 

 that of the fertile hyphse, but the refrangibility differs greatly in 

 different parts of the same hyphse. Their mode of formation is very 

 similar to that of the fertile hyphse. As they develope they carry up 

 with them the spores, which become attached to them, outside the 

 outer peridium, where they are ready for dissemination. 



The spores appear to retain their power of germination for a period 

 of from three to four months. They germinate either directly with 

 the formation of a septated germinating filament, or with the inter- 

 vention of a single cylindrical sporidium produced from each spore. 

 The germinating filaments grow to a length of 400 fx ; their further 

 development was not observed. There is no reason for believing that 

 the genus has any heteroecism or alternation of generations. 



As regards the systematic position of G. apMola, the author does not 

 agree with any of the views hitherto brought forward, but considers it 



Ser. 2.— Vol. IV. T 



