132 Rayner.—Obligate Symbiosis in Calluna vulgaris . 
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EXPLANATION OF PLATE VI. 
Illustrating M. C. Rayner’s paper on Obligate Symbiosis in Calluna vulgaris. 
Figs. 10, 15 b , 16, 17, 18, 19, 20 = photographs. Fig. 21 = microphotograph. Figs. 11, 12, 13 = 
camera lucida drawings. Figs. 14, 15 a = drawings. 
Fig. 1 a. Ovarial infection. Part of a longitudinal section of the unopened fruit, showing 
seeds still attached to funicles. Mycelium in all parts of the ovary tissues, and traversing the 
spaces between ovary wall and seeds, &c. h. = hyphae. x 60 diam. 
Fig. 1 b. Part of the section shown in Fig. 1 a, more highly magnified, h. = hyphae ; 0. = ovary 
wall; t. = seed, x 300 diam. 
Fig. 2. Cell from mesophyll (bundle sheath) of the cotyledon filled with hyphae. h. = hyphae ; 
v. = vessel in median vascular strand; chi. = chloroplast. Camera lucida drawing from a section 
22 [x stained cotton blue in lactic acid. Leitz obj. 6 ; Zeiss compens. oc. 12. 
Fig. 3. Mycelium of mycorrhizal Fungus outside root; hyphae continuous with those in cells. 
r. = root; v. = * vesicles ’. x 330 diam. 
Fig. 4. Mycelium of mycorrhizal Fungus, from pure culture of same on Calluna-Qn tract gelatine 
v. = ‘vesicles’, x 330 diam. 
Fig. 5. Transverse sections of successive leaves near apex of shoot, g . = groove on abaxial 
side; s. = air-space, x 100 diam. 
Fig. 6. Longitudinal section of leaf parallel to upper surface, c. — crystals of calcium oxalate, 
x 68 diam. 
Fig. 7. Coils of mycelium between adjacent leaves, penetrating the epidermis and mesophyll on 
either side. e. = epidermis ; m. = mesophyll cell; h. — hypha. From longitudinal section of shoot, 
stained Benda hsematoxylin. X 540 diam. 
Fig. 8. Mycorrhizal Fungus. Hyphae and pycnidia from pure culture on rice. Six weeks. 
p. = pycnidium. x 75 diam. 
Fig. 9. Mycorrhizal Fungus. Pycnidium more highly magnified after escape of pycnidiospores. 
p. = pycnidium; s. = pycnidiospore. x 210 diam. 
