VEGE TA TIVE REP ROD UCTION. 



217 



the spores may be brought to the surface and set free. Thus 

 the spore-beds of parasitic fungi commonly blister the surface 

 of the host bv bfting up its outer tissues {co, fig. 210). 



313. Spore-chains. — Spores maybe produced either singly 

 at the ends of the branches or in chains. When produced in 

 chains, the youngest spore may be at the base or at the apex 

 of the chain. The first method is much more common than 

 the second. In the second case each spore must arise as a 

 bud upon an older spore, budding itself to form a younger one 

 (fig. 211). The spores in such a chain are limited in number. 

 They develop rapidly, and all are loosened at about the same 

 time. Those chains which have the oldest spore at the apex 



Fig. 212. 



Fig, 212. — An outline sliowing the formation of a basipetal spore -chain of the Ijlue-green 

 mold \r^<^nicilliuin glaiicmti). /'.branch of spore-bearing hypha, budding beneath 

 two older spores. Across the narrow neck a partition wall is formed, the spores round 

 off, and from this wall a de\ice, c, for loosening the spores is developed. The 

 terminal spore is oldest. Highly magnitied.— -After Frank. 



Fig. 213. — Longitudinal section through the edge of a gill of a mushroom {Co^ritins) 

 after spore-formation is completed. /. interwoven hypha^ of the gill, brandling to 

 form the hvmenium, composed of the paraphyses, /, the cystidia, c, and the ba- 

 sidia, /'. The latter gi\'e rise to four slender branches, whose tips enlarge to form each 

 a single spore. / and c do not produce spores. Maguitied 300 diam. — -After Brefeld. 



are produced by the continued division of the branch by 

 transverse partitions, usually preceded by budding of th.e 

 apex, often described as constriction (b, fig. 212). Beneath 



