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268 ~~ Structural and Physiological Botany, 
and Leronospora, sporangia are formed instead of spores — 
on the basidia. Spores which become abstricted in this 
way from the apex of filaments have been termed conddia ; 
if formed in special receptacles or pycnidia, they are stylo- 
Spores. 
3. In asct or thece (Fig. 399). The spores, here called 
ascospores, thecaspores, or endospores, are usually formed 
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Fic. 399.—I. Transverse section through a receptacle of Ascobolus pulcherrimus 
(magnified) ; II. a part of a receptacle consisting of asci in various stages of de- 
velopment, and paraphyses (more strongly magnified). 
simultaneously in definite number (in most species eight), 
in the interior of a sac-like cell, the Ascus or Theca, which 
they do not entirely fill up. The asci are usually surrounded 
by paraphyses, t.e. unbranched unicellular or multicellular 
hairs which are formed beside them, usually in large numbers 
and running in the same direction. Special receptacles in 
which asci are formed are called perithecia (Fig. 395, p. 266). 
The further behaviour of the spores also exhibits a 
variety of differences. ‘The Swarmspores or Zoospores 
break through the wall of the cell in which they are 
formed and which is called a zoosporangium ; and then 
swim about for some hours or even days, as if endowed with 
voluntary power of motion, by means of their vibratile cilia; 
after which they become fixed and develope into new plants _ 
(Figs. 400, 401). The greater number of spores, however, 
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are not endowed with motion of this kind. In some in- — 
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