470 APPENDIX II. 



Pelargonium zonale (so called " Geranium "), for glandular hairs, 97. 



Petioles. Fresh, or in alcohol. 



Pellionia, Daveauana. Green starch-formers in young stem, 60. Fresh. 

 Penicillium crustaceum (Blue Mould), 323. Obtained on a piece of moist 



bread under a bell-jar. 

 Peronosporese. See Phytophthora. 

 Phajus. Half-grown pseudo-bulbs used for ieucoplasts, 59. Fresh, or 



fixed with picric acid. 

 Phaseolus vulgaris (Bean). Starch, 17. Bean flour ; or obtained by scraping 



a cut bean. 



Phcsnix dactylifera (Date). Structure of endosperm, 73. Date-stones. 

 Phycomycetes. See Mucor Mucedo. 

 Phytophthora infestans (Potato disease), 318. Diseased leaves of potato. 



Fresh. 

 Picea vulgaris (P. excelsa). Female cones and fertilisation, 372. Cones. 



Alcohol. Mid-June. Fertilisation is completed in June ; the exact 



date for the locality varies from year to year. Hence cones should 



be gathered daily from 1st June, and the scales, separated from one 



another, placed in absolute alcohol. Before investigation the scales 



must be laid for at least twenty-four hours in a mixture of equal 



parts of glycerine and water. 

 Pilobolm crystallinus. On dung cultures, 327. 

 Pinnularia viridis, 255. Fresh. Not infrequent in standing and running 



water. 

 Pinus sylvestris. Bordered pits, 74 et seq. Pieces of old stem in alcohol. 



Structure of stem and development of bordered pits, 137. 



Young steins, and. pieces of outer part of old stems, cut in June or 



July, and laid in alcohol. To be placed in glycerine and alcohol 



before using. 



Male flowers, 367. Male cones. Alcohol. May or early in 



June. Laid in glycerine and alcohol before using. 



Female flower, ovule, 370. Young cones. Alcohol. May or 



June. Glycerine and alcohol before using. 



Pollination, 371. Young cones as above, but fresh. 

 Pisum sativum (Pea). Structure of seed, and aleurone grains, 25. Ripe 



peas. Dry. 



Pleurosigma angulatum, 259. A diatom used widely as a test-object. 

 Plum. See Prunus domestica. 

 Polypodium vulgare (Polypody fern). Reproduction, sexual and asexual, 



357. Prothallia and fertile leaves. Fresh. 

 Polytrichum juniperinum. Structure of stem, 230. Stems. Fresh, or in 



alcohol. 



Antheridia, 346. Plants in "flower". May. Fresh, or in 

 alcohol. 

 Potato. See Solanum tuber osum. 



starch. Commercial, from a chemist. 



