PLATE 29. Lichens. 



Figure 



1. Fragment of the thallus of Parmelia parietina, Ach., with young apothecia and 



spermagonia (near the edges of the lobes) . 



2. Vertical section of one of the spermagonia and the part of the thallus in which 



it lies. This section shows the upper and lower cortical layers of the thallus, 

 with the intermediate filamentous medulla and its globular gonidia. 



3. Fragment from the wall of the above spermagonium, more magnified, to show 



the articulated filaments (spermatophores) which bear the spermatia. 



4. Spores of the same, treated with iodine ; the dark portion represents the proto- 



plasmic contents. 



5. A spore which has germinated. 



6. Fragment of a vertical section through the apothecium of Parmelia stellaris, Fr. 



The upper part is the fertile layer, or thalamium, composed of thecce with 

 spores and paraphyses ; this rests on the hypothecium, beneath which is a 

 portion of the medullary layer, with gonidia. 



7. Ripe spores of the same. 



8. Ripe spores, germinated and not germinated, treated with sulphuric acid, and 



broken, showing the clear endospore inside the hard exospore. 



9. Ripe spore of Verrucaria nitida, Fr. 



10. Isolated spermatia from the spermagonia of ditto. 



11. Ripe spores of Peltigera horizontal^, Hoffm. 



12. Fragment of the thalamium of Sphcerophoron coralloides, Pers., with thecce in 



different stages of development, and free ripe spores. 



13. Vertical section of a spermagonium of Collema Jacobecefolium, D.C., with sper- 



matia escaping. Imbedded in the thallus are seen the moniliform gonidial 

 filaments. 



14. Isolated articulated filaments from the same. 



15. Isolated spermatia from these filaments. 



16. Vertical section of a spermagonium of Cladonia rangiferina, Hoffm., with sper- 



matia escaping from its orifice. 



17. Ripe spores of Urceolaria scruposa, Ach., seen in water. 



18. Fully developed spores of Umbilicaria pustulata, Hoffm. 



19. Ripe spores of Lecanora parella, Ach. 



