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OBSERVATIONS ON THE VOLVOCACEAE OF MADRAS*
BY
M. O. Parthasarathy Ayyangar, M.A.,
Acting Professor of Botany, Presidency College, Madras.
Though there have -been some very valuable contributions by algologists like Fritsch (3 and 4), West (6) and (7), Wallich (5), Zeller (10), and others, on the Fresh-water Algal Flora of the Indian region, there has been practically, with the exception of some stray notes, (l, 2, and 8 page 178), no account whatever, either syste- matic or ecological of the Volvocaceae of India.
Fritsch (3) in his systematic account of the Algal Flora of the Tropics does not refer to the Volvocaceae at all, though records of their occurrence have not been wanting, one of them, (Fleodorina), having been recorded by himself (2) from Ceylon. Again West G. S. 9) has recorded some new African species of Volvox. He says (8, (page 182), " Volvo x africanus is known to occur only from the plankton of Albert Nyanza." He has also recorded Pleodorina illinoisemis from Madras (8, page 178). He, however, expresses the opinion that the members of this family are on the whole cold water types (8, page 429). It would therefore appear that the mem- bers of the Volvocaceae are regarded by European algologists as preeminently cold water types. The primary object of this paper is to draw attention to the very common and abundant occurrence of this family in Madras, a typically semi-dry tropical place. In fact as may be seen below they attain their maximum development only during the warmer parts of the year.
Climatic Details
Madras is quite different from the other parts of India as regards its supply of rain. While all -the other parts of India get their maximum supply of rain during the months June to September from the S. W. or Summer Monsoon, the Madras coast districts (from Ganjam to Negapatam) get their chief rain supply during the months October to December from the N. E. or Winter Monsoon. The S. W. Monsoon is only of minor importance on the Madras coast and moreover does not directly bring any rain to Madras. During the breaks in this monsoon on the west coast and towards
- A paper read before the Botanical Section of the Indian Science Con-
gress Meeting at Nagpur, 1920.
