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A TEXTBOOK OF THEORETICAL BOTANY 



perithecial zone. Other hyphae soon grow and surround the coil, thus form- 

 ing a small circular knot of tissue. As growth continues in the inner tissue 

 the cells which will form the wall of the perithecium not only increase in size 

 but additional hyphae grow up between the pre-existing ones. Thus the wall 

 enlarges while at the same time a cavity develops between the ascogonium 

 and the wall, probably as a result of the breakdown of the inner hyphae to 

 provide food for the developing sexual apparatus (Fig. 282). Many perithecia 

 begin to develop, although only some mature, and since these enlarge till they 



Fig. 282. — Hypoxylon coccineum. Development of the perithecium. A, Surface 

 view of coiled hyphae. B and C, Budding of ascogenous hyphae from 

 ascogonium. D, Section through perithecium with developing ascogonia. 

 {After Lupo.) 



reach the peripheral zone while those which fail to develop do not, it follows 

 that there appears to be a progressive development of perithecia from the 

 centre outwards. 



Inside the young coil there appears a row of broad cells which are 

 irregularly rolled up and full of protoplasm. This is termed the Woronin 

 hypha. It increases in length, size and in the number of its cells. Certain 

 of these cells enlarge and eventually separate from one another to form 

 separate ascogonia. They enlarge very greatly, assuming quite irregular 

 shapes and apparently contain many nuclei. 



The basal wall of the perithecium now grows upwards into the cavity 

 from below, so that the ascogonia become embedded in the floor of the 

 perithecium, and here they continue to develop. From these ascogonia 

 ascogenous hyphae are budded out, and into them nuclei from the ascogonia 

 migrate. 



The further development of the ascogenous hyphae into asci has not 

 been followed, but by analogy with other groups it is reasonable to assume 



