248 
Poulton . — The Structure and Life-history of 
Periphyses line the ostiole and the upper portion of the perithecium, 
and from the base, asci containing ascospores are developed in the usual 
manner. 
4. The spores are at first unilocular, later they become bilocular, 
and finally quadrilocular. They may germinate in any of these con- 
ditions. 
The spores often germinate while still within the perithecium and the 
resulting hyphal network is eventually expelled through the ostiole and floats 
freely in the water. This no doubt serves to entrap any free-floating cells of 
Pleuroccocus , and it may be regarded as a specialization to ensure the union 
of the two constituents. 
Works referred to. 
Ach. L. Univ. : Acharius, Lichenographia Universalis, 18 io. 
Ach. Meth. Lich. : Acharius, Methodus Lichenum, 1803. 
Ach. Syn. Meth. Lich. : Acharius, Synopsis Methodica Lichenum, 1814. 
Bonnier, G. : Recherches sur la synthese des Lichens. Annales des Sciences naturelles, Ser. vii, 
Bot. vol. ix. 1889. 
Chodat, R. : Polymorphisme des Algues. Geneve, 1909. 
Crombie : British Lichens, 1894. 
E. Bot. Suppl. : Supplement to English Botany, 1834. 
Leight. Ang. Lich. : Leighton, Angiocarpic Lichens. Proceedings of Ray Society, 1851. 
Leight. Lich. FI. : Leighton, Lichen Flora of Great Britain, 1879. 
Lind. Brit. Lich. : Lindsay, Popular History of British Lichens, 1856. 
Mudd, Man. Brit. Lich. : Mudd, Manual of British Lichens, 1861. 
Wahl. FI. Suec. : Wahlenberg, Flora Suecica, 1826. 
EXPLANATION OF PLATES XIII AND XIV. 
Illustrating the paper by Miss Poulton on the Structure and Life-history of Vernicaria mai’gacea. 
PLATE XIII. 
Fig. 1. Lichen thalli growing upon stone. § nat. size. 
Fig. 2. Thalli growing in close proximity and becoming coalescent. § nat. size. 
Fig. 3. Vertical section of young thallus. a , algal cells scattered in hyphal network, h. x 750. 
Fig. 4. Vertical section of older thallus, showing chains of algal cells, c. h , fungal hyphae. 
x 750- 
Fig. 5. Thallus, vertical section, showing algae, a , aggregated near dorsal and ventral surfaces. 
h, fungal hyphae. X 750. 
Fig. 6. ? Soredium. x 800. 
Fig. 7. Vertical section of thallus, showing first stage in formation of perithecium. a , elevation 
of thallus caused by conical mass of hyphae, b. x 80. 
Fig. 8. Ditto, a , base of thallus with algal cells; b , hyphae interweaving to form pseudo- 
parenchymatous mass of tissue, t. x 800. 
