2 2 FTRS T GRO UP. — THA LL OPII\ 'TES. 



The trichogyne also suffers characteristic changes in consequence of fertilisation. 

 While the cells of the ascogone increase in size, those of the trichogyne lose a portion 

 of their original volume ; the transverse septa swell up into thick strongly refractive 

 nodes, so that the trichogyne which was before of uniform thickness assumes a 

 nodose appearance ; the protoplasmic contents of its cells also become brown. The 

 phenomena of reproduction are quite similar in other Collemaceae. Physnia com- 

 pactum is peculiar in one respect ; the apothecia are formed in the tissue which con- 

 stitutes the envelope of the spermogonia. From the base of this receptacle hyphal 

 filaments grow up and form procarps. This species may therefore be said to be 



/TSji* /f KTw 



FIG. 8i. Anapiychia ciiiuiis, a small portion oi the apotheciun 

 of the thallus, y the subhymenial layer, p paraphyses of the hymeniur 

 stages of development ; in i the young spores are not yet septate, in 

 protoplasm in which they are imbedded is contracted by tlie drying 

 was made. Magn. 350 times. 



in vertical section ; »i medullary layer 

 ; between them are the asci in different 

 2 — 4 the spores are more advanced ; the 

 ip of the Lichen before the preparation 



hermaphrodite, since spermatia and carpogone are derived from common hyphal 

 layers. The envelope of the apothecium in this case is not as in CoUeina a result of 

 fertilisation, but was in existence before as the envelope of the spermogonia. 



The club-shaped spore-sacs (asci) of the Lichens resemble those of the Pyrenomy- 

 cetes and Discomycetes in every important point ; their wall is often very thick and 

 has great power of swelling; the spores too (Fig. 82), as in the Fungi just mentioned, 

 are the result of a process of free cell-formation, in which a portion of the protoplasm, 

 and often a considerable portion, remains unused. The normal number of the spores 

 is eight, sometimes only one to two, as in Umbilicaria and Megahspora, from two to 

 three or four to six in some species of Pertusaria ; some hundreds even are found in one 



