ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 227 



Observations on Monosporangial Discs in the Genus Liagora. — 

 M. A. Howe [Bull. Torreij Bot. Club, 1920, 47, 1-8, 1 pL, figs, in text). 

 An explanation of the structures briefly described and figured by Kiitzing 

 in 1858 (Tab. Phjc. YIIL, pi. 90). The structures in question are 

 small flat orbicular discs lying on the general surface of the plant or 

 somewhat immersed among the assimilatory filaments. They are of a 

 deeper red colour than the main Liagora plant ; they send down few 

 or numerous root-hairs from their ventral (proximal) surface in among 

 the assimilatory filaments ; and they bear on their dorsal (distal) surface 

 a few sporangia, the contents of which remain undivided, so that they 

 may be referred to as monosporangia. Long, colourless, gelatinizing 

 hairs may usually be seen arising from this outer or dorsal surface. It 

 might be supposed that they are either independent organisms or 

 perhaps obligate epiphytes of various species of Liagora ; or that they 

 result from the germination of carpospores and represent a non-sexual 

 alternating phase in the life-history of the genus. But the truth seems 

 to be that these discs arise from gonidia, gemmae, or aplanospores derived 

 from the terminal or subterminal cells of the assimilatory filaments of 

 the Liagora ; and more often on male than on female plants. The 

 development of the discs varies in certain details according to the 

 species they represent. The author has made a prolonged and careful 

 study of these discs on four of the West Indian species, L. ceratioides, 

 L. valida, L.farinosa and L. pinnata, and describes the variations in 

 the development of each. The mature discs are suborbicular and are 

 more or less similar in these four species. Fertile discs are mostly 

 90-230 /x broad (not including the mucous envelope), though in 

 L. farinosa, the largest species of the four named, they may reach a 

 diameter of nearly 400 fx. The monosporangia are ellipsoid, ovoid and 

 obovoid. To what these give rise on germination has not been deter- 

 mined, but there seems to be some ground for believing that they 

 produce monosporangial discs like those from which they sprang. In- 

 ferences that young sporelings associated with a Liagora represent stages 

 in development of the Liagora itself demand vigorous confirmation ; but 

 the almost constant association of Acrochsetium-like forms with various 

 species of Liagora is a suspicious circumstance that deserves investigation. 

 Finally, he points out criticisms that may be raised on his conclusions, 

 since, as he frankly acknowledges, he knows of no analogy among other 

 Rhodophycese for the state of things here described. He suggests that 

 a study of living material, cultural experiments and cytological investi- 

 gation would settle the question, although he believes his explanation to 

 be correct. E. S. G-. 



Appendix to " Oceanic Algology." — A. Mazza {Nuova Notarisia, 

 1920, 31, 93-160). Further additional notes on species belonging to 

 sub-families Mychode^e and Callymenie^e, and to the family Rhodo- 

 phyllidaceag. The author devotes considerable attention to Calhjmenia 

 crihrosa Harv., describing its structure and perforations, and comparing 

 it with perforated species of Ph^eophyceae, Hydroclathrus, Agarum and 

 Thalassiophylliim, as well as with other Floridese. The two doubtful 

 species of Jleristotheca — 31. Diichassaingii J. Ag. and M. Fergussonii Grun. 



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