330 



OBSERVATIONS ON THE VOLVOCACEAE 

 OF MADRAS * 



BY 



M. 0. Parthasaeathy 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. 



