F. E. FRITSCH. 



It is hardly likely that this list approaches completeness, but it is probably fairly 

 representative of the general character of the floating flora. In particular the 

 number of free-floating Diatoms is certainly appreciably greater. 



The material included a considerable number of samples from the Gap pond, 

 Winter Harbour, collected on four distinct occasions during 1902-1904. A critical 

 survey of these samples has failed to give any marked indication of periodicity, 

 although the period of collecting is spread over more than two months, which 

 in milder climates is quite enough to afford a prominent periodical change. The 

 samples collected in February (i.e. fairly late in the Antarctic summer) were rather 

 richer in heterocystous Cyanophycese than the others, but this may well be due 

 merely to chance. No doubt the severe climatic conditions do not admit of a 

 rapid and abundant development of any one form or set of forms during the 

 short summer, and hence there can be no marked periodicity. One altogether 

 tends to come to the conclusion that reproduction in the bulk of the Antarctic 

 Algge must be a very slow process and possibly several seasons elapse before a 

 new generation reaches to maturity. In the case of the unicellular green repre- 

 sentatives of the flora matters will, however, be different, and the cyst-formation 

 of Chlamydomonas subcaudata Wille, described on p. 8, indicates the alternation 

 of a marked resting-stage and a motile stage in the annual cycle. 



In conclusion the following Table will serve (in further illustration of some 

 of the above remarks) to contrast the algal floras of Kerguelen and South Georgia, 

 the South Orkneys and the regions from which the ' Discovery ' and Shackleton's 

 Expeditions collected their Algse. 



* Compiled from Reinsch's papers ; see footnote on p. 3. 



t Cf. Fritsch, op. cit. 



t Compiled from the present report and that of Messrs. W. and G. S. West (op. cit.). 



