_■ ^ 



K 1 



r - 



^ ^- 



26 



MISS B. M. BRISTOL ON 



XIIL 



(Scliroet.), Freeman, '^Ob 



) 



End 



Jabresber. Scliles, Ge?olIscb. 1883, p. 81. 



Cells about 90 /a long and (50 ^u broad, or smaller ; cell-'\^^all 7-10 /^ tliick, 

 unequally tbickencd^ being often constricted in places, witb gelatinous layers, 

 produced into a colourless neck. Cell-contents often red. Sexual zoogonidia 

 are produced. Tbe alga procluces irregularly globose or ovoid tubercles tbat 

 are oEten red on tbe leaves of tbe bost-iilant. 



JJab, lu tbe iniercellular spaces of leaves of Mentha aquatica and PejAis 

 Porlida. 



In conclusion, I wish to express my tbanks to Prof- G, S. West for bis 

 suggestion tbat I should undertake this work, and for bis valuable help, 

 especially in the obtaining of literature. 



The Bptanical Laboratory, 



University of J3irniingliam. 



EXPLANATION 01^^ THE PLATES. 



Platp: 1. 



Rcqircsentiny stained preparations of C^i.oi\QQiiYT\Ki\:'^i Lkmn^. All figs. Xl435. 



Fig. 1. Section of cell embedded iu sub- epidermal tit^sue of Lemna trisuka^ showing the 



tubular neck, a central nucleus^ a massive radiating cbloruplast, and several pyre- 

 noids in the periphery of the cliloroplast. (N.B. — Contents shiunk owing to use 

 of reagents.) 



Figs. 2 & 3. Sections of fairly typical cells througli the nncleusj showing the radiating 



chluroplast with fused parietal plates containing a number of pyrenoids. 



Figs. 4-^6. Serial sectionp of a single typical cell to illustrate the structure of the chluro- 

 plast: 4, section through the nucleus, showing small central axis with radiating 

 branched arms and fused parietal expansions; 5, more tangential section with 

 radiating arms cut obliquely ; 6, section near periphery, showing the expanded 

 parietal portions of the chloropla^t fused together. 



Figs, 7 & 8, Padial sections of cells from which the fusion of the parietal expansions of 



the chloroplast is partly (7) or completely (8) absent. 



Figs. 9-lL Sections of cells in vrhich the central portion of the chloroplast is mucli 



reduced while the peripheral poitiou is correspondingly developed, giving the 

 appearance almost of a single parietal chloroplast ; figs. 9 k 10, radial and 

 tangential sectii>ns of the same cell* 



Figs. 12-14 i^ 16. Sections of cells in which there is great development of the axial portion 



and radiating arms of the chluroplast and the consequent production of a very 

 massive chloroplast. Fig-^. 1^-14, serial sections of the same cell. 

 Fig, 15* Section of a cell in which one of the pyrenoids is further from the periphery than 



is usual- 



(N.B. — Figs. 8, n, 12, & 16 are represented w^ithout cell-walls.) 

 c. colourless cytoplasm, ch. chloroplast, k, iiaryosome, n. nucleus, nk. necli, 

 py, }>yrenoid. 



k I 



