6 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 (/.e. fairly late in the Antarctic summer) were rather 
richer in heterocystous Cyanophyceze than the others, but this may well be due 
merely to chance. No doubt the severe climatic conditions do not admit of 
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 
Alow 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 Alge. 
* Discovery’ 
SourH ORKNEYsS.t AND SHACKLETON’S 
EXPEDITIONS.{ 
| SoutH GEORGIA AND 
KERGUELEN,* 
Genera. Species. Genera. | Species. Genera. Species. 
Protococcales : 18 28 13 24 5 13 
Siphonales (including Vaue heria) : 1 6 a6 ne 58 2B 
Ulotrichales (including O5edoyoniacerr ) 15 25 4 5 2 7 
Conjugate . 5 : : ; 9 3 4 5 1 
Heterokonte. 5 ; : yal 1 i 1 
Pheo- and Rhodophycece. : a 2 2 So | as Do | ae 
Chroococcucece : : : : 5 a 8 | 10 9 | 20 
Oscillariee 4 4 2 | 5 6 41 
Heterocystous Cyanophyce 10 26 3 3 5 16 
Diatomacece . 18 3D 9 | 15 19 42 
* 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. 8. West (op. cit.). 
