Professor G. S. West's “ Algce 
5i 
derivation from Protococcaceous forms should have found mention. 
The genus Chlorospliceva, combining as it does occasional vegetative 
division (in one species even with the formation of short filaments) 
with the customary propagation by zoospores, could equally well 
have been the starting-point of a filamentous series. 
The author upholds his earlier view that the Desmids arose 
from a filamentous ancestry, although it cannot be said that the 
evidence brought forward is at all conclusive. The statement on 
p. 377 that “ in Desmidium cylindricum and in the presumed 
‘abnormal ’ cases of conjugation in Hyalotlieca dissiliens one is pro¬ 
bably witnessing the type of conjugation which was prevalent in the 
ancestors of the Desmidiacese,” might equally well be regarded as 
evidence of a specialisation accompanying the adoption of a colonial 
habit. Lower down on the same page the author himself describes 
the filamentous condition as secondary. We are more inclined to 
regard Desmidiacese and Zygnemaceae as divergent lines from a 
common ancestry, and in this connection Oltmanns’ distinction 
of the family Mesotaeniaceae (which should certainly include 
Netrium , and possibly also Gouatozygou and Geuicularia ') was in 
our opinion a great advance. This family, including as it does 
forms with all the main types of chloroplast-structnre found in 
Zygnemaceae, might well be regarded as a remnant of the ancestry 
of the Conjugatae. The behaviour of the zygospore on germination, 
as far as it is known, and the simple character of the cell-wall 
would be quite in accordance with this theory. 
There are a number of minor phylogenetic points that call for 
mention. We do not understand why Gonium is placed on a side- 
branch, whilst Pandorina, Eudorina, etc., are put in line in the 
phylogenetic scheme on p. 182. Seeing that all Volvoceae pass 
through a Gonium- stage in the development of their daughter- 
colonies (a fact which is not mentioned), it would seem that 
Gonium should naturally come in line with the others. Nor is it 
clear why, on p. 282, Aphanochcete is placed as an offshoot from 
the line of evolution of Draparnaldia ; to our mind the former 
genus is best derived from forms like Stigeoclonium (a name now 
readopted in place of Myxonema) by suppression of the upright 
branches and specialisation in the reproductive process. Stichococcus 
is probably better regarded as a reduced member of Ulotrichaceae 
than as being on the upgrade of evolution, and the position of 
Geminella in the phylogenetic scheme may also be questioned. 
We are not prepared to accept the statement that “ the principal 
members of the Chaetophoraceae have doubtless originated directly 
from Ulotrichaceae by the branching of the thallus ” (p. 293); it 
seems more likely that they diverged from the line of evolution of 
Ulotrichaceae at a very early stage. 
In the treatment of the Chlorococcineae some mention might 
have been made of points of contact with Fungi like Rhodochytrium 
and Synchytrium. Similarly, in dealing with Vaucheria, some 
reference to the views that have been held as to its possible rela¬ 
tionship with the ancestry of Oomycetes might have been 
incorporated. 
1 Making it synonymous with West’s Saccodermas. 
