116 MR. H. M. WARD ON THE STRUCTURE, DEVELOPMENT, 
Fig. 8. Specimens of the adult Lichen slightly magnified. The upper consists of two unbranched thalli; 
the lower figure represents one much branched. The dark spots in the white porcellaneous 
matrix are fruit-bodies. 3 
Fig. 4. Portion of a grey-green thallus removed from the leaf. In connexion with the Alga are Fungus- 
hyphe, some of which radiate from points at the edges. Two black pycnids have also been 
formed in the substance of the thallus ; and from the apical pore of one of these minute colourless 
stylospores are escaping. Gundl. 3, oc. 4. 
Fig. 5. Portions of the alga more closely examined. The thallus consists of radially arranged rows of 
cells and of prolongations of these. Each cell contains a general matrix of green-coloured 
protoplasm, in which are granules and oily drops, some of which are coloured red and orange : 
a, fresh, in water, Zeiss D, oc. 2; 0, ditto, Zeiss E, ос. 4; с, decolourized in alcohol and 
glycerine, Zeiss D, oc. 4. 
Fig. 6. Portions of similar thallus. The oily orange-coloured globules are more or less diffused or in 
abeyance (а), or form large drops (4) in the firm-walled cells; іп (с) they have become disor- 
ganized, and colourless resin-like bodies are formed. Fig. 6d shows a not uncommon example 
of the loose branching of the thallus. Fig. 6. Zeiss J, ос. 4; 6 & с, Zeiss Е, ос. 4; 
d, Zeiss D, oc. 4. 
Fig. 7. Portion of vertical section through a leaf of Michelia and its superposed Alga; the razor has 
passed through the tip of a branch of the latter where two “ barren hairs” arise. Acetic acid 
and glycerine. Zeiss D, oc. 4. 
Fig. 8. Similar section, passing through a broader portion of thallus and its rhizoids: the upper 
“ palisade cells” of that portion of the leaf covered by the thallus are becoming divided by 
horizontal septa, as a cork meristem. Alcohol and glycerine. Zeiss D, oc. 4. 
Fig. 9. Similar section through leaf and body of Alga: cork meristem &c. as before. Decolourized in 
alcohol, and treated with KHO. Zeiss D, oc. 4. 
Prate XIX. 
Fig. 10. Similar sections through leaf, the thallus (in a) and details of cell-contents omitted for sim- 
plicity: at 0, through portion of leaf not affected by the epiphyte; а, through portion on 
which the Alga had developed. In the latter the palisade cells have developed cork meristem, 
the outer cells being already brown and dead; in the deeper cells the divisions are more 
irregular. Zeiss D, oc. 4. 
Fig. 11. Portion of thallus, from section similar to last : it is external; and the rhizoids are closely com- 
pressed. Zeiss Е, ос. 4. 
Fig. 12. Similar section through leaf and more loosely grown thallus, showing the rhizoids and cuticle of 
of the latter in detail; the razor has also exposed a young zoosporangium. The cuticle and 
epidermis of the leaf are dead; but the rhizoids have not penetrated the leaf. Imm. 70, oc. 3. 
Fig. 18. Vertical section through leaf of Citrus, оп which the Alga is flourishing. The latter has 
developed in the epidermis, pushing up the cuticle and breaking down the cells. Deep down in 
the palisade cells, horizontal partitions have formed, resulting, as before, in the formation of 
dead corky tissue. All healthy growing parts are left uncoloured. Two “ barren hairs” are 
protruded through the cuticle. Zeiss E, oc. 4. 
Fig. 14. Portion of cork and cork meristem from section similar to last, treated with Н, SO, and iodine 
solution and washed. The cork remains yellow-brown and resistant, the meristem walls become 
blue, swell up, and finally dissolve. 
Figs. 15 & 16. Portions of Alga-thallus, viewed obliquely from above (Hartn. 4), to show the relations of 
the “barren”? and “ fertile hairs” to the cellular thallus. Іп fig. 16 are also shown the 
