Palaeontoloo^ie. — Alo^ae. 269 



'& 



spermeae and Cordaiteae (different as they appear) especially in the 

 seed-structure and in some points in their anatomy. 



Arber (Cambridge). 



Stopes, M. C, A Note on wounded Calamites. (Annais of Bo- 

 tanv. Vol. XXI. p. 277—280. With a plate and 4 diagrams in 

 text. 1907.) 



In the specimens described in this paper the wound extended 

 to the pitch, breaking through the vascular cylinder. As a result, 

 in addition to callus-wood, new wood has been formed in the pitch 

 cavity, in inverse orientation to the normal Strands. A wound-cam- 

 bium is formed in the neighbourhood of the injury, curving in and 

 out round the primär}^ bundles, and adding new tissue where there 

 was room for it. Thus the injured primary Strands, with small 

 quantities of secondary tissue associated with them, have been cut 

 off and isolated from the rest of the wood. Arbsr (Cambridge). 



Fritsch, F. E., A general Consideration of the Subaerial 

 and Fresh-water Algal Flora of Ceylon. A Contribu- 

 tion to the study of tropical algal ecology. Part. I. — 

 Subaerial Algae and Algae of the inland Freshwaters. 

 (Proceedings of the Royal Society of London. B. Vol. LXXIX. 

 p. 197 — 254 with iive textfigures and one map. 1907.) 



Careful study of the algal flora of Ceylon (and presumably of 

 any other part of the tropics) reveals that composition of the flora is 

 quite a distinct one and that the development of the subaerial algal 

 Vegetation is remarkably luxuriant. One ot the most important fea- 

 tures of the flora is the great predominance of the Cyanophyceae 

 which ist most marked in the case of the subaerial algal growth ; 

 here green Algae (and even Bryophytes, except in situations pro- 

 tected from the strong light) are practically wanting. Aquatic algal 

 growth also exhibits a ver}' marked blue-green dement, especially 

 in the larger pieces of water. This great predominance of Cyano- 

 ph3^ceae appears to be due to a diversity of adaptations (to light, 

 temperature, risk of desiccation, etc.), most important of which is 

 the presence of a protective colouring-matter (phycocj^anin) side by 

 side with the Chlorophyll. A striking confirmation of this is found in 

 the fact that the only other Algae which are successful in a subae- 

 rial habitat are species of the genus Tventepohlia , the haemato- 

 chrome in their cells affording the necessary protection to the 

 Chlorophyll. Second in importance to the Cyanophyceae in the 

 aquatic Vegetation are filamentous Conjugates, of which Spirogyra is 

 most frequently met with; in shaded waters (especially if of small 

 dimension), Conjugates may completelj' dominate the algal growth. 



The species of Spirogyra are mostly broad forms with many 

 spirals; infolded end-walls have not been observed in the Ceylon- 

 material Desmids often play a great part, especially in the smaller 

 pools and ditches. It is noticeable that filamentous Desmids are 

 rather abundant in the lowland pools, very scarce in those of the 

 uplands (6000 feet; climate and average temperature almost tempe- 

 rate); judging from analogy, it is possible that the marked filamen- 

 tous tendency amongst the Desmids of the lowland pools may be 

 due to the relatively small percentage of dissolved oxygen in the 

 water. The Desmids are of importance as an ecological characteristic 



