40 
Some Aspects of the Alga;. 
variability in the different species and genera, are happily compared 
with the leaves of the higher plants. The general phylogenetic 
considerations that are given, however, are not so fortunate, and 
Schimper’s view is, we think, rather unfairly treated. The author 
seems to fall into the too common mistake of supposing that the 
conditions obtaining in growing points can give information as to 
primitive ancestral stages. Though Schimper’s theory cannot be 
expected to express satisfactorily the modern standpoint involving 
the polyphyletic flagellate origin of many at least of the algrn, it 
probably contains a large part of the truth, and an attempt should 
be made to re-state it in the light of our knowledge of the primitive 
chromatophores of the Volvocaceae on the one hand, and the lower 
Heterokontae on the other. 
In the section on Pyrenoids there is no reference to the work 
of Timberlake (Annals of Botany, 1901) who showed, for Hydro - 
dictyon, that the apparently fundamental difference between 
“pyrenoid-starch” and “stroma-starch” hypothecated by Klebs 
has no real existence, the so-called stroma-starch being merely 
grains of pyrenoid-starch pushed out into the substance of the 
chromatophore. Whether this applies also to the other pyrenoid- 
bearing forms in which stroma-starch can be demonstrated, has 
not, so far as we are aware, been shewn, but Timberlake’s careful 
method of investigation certainly ought to be applied to such forms. 
In the chapter on Nutrition, a condensed account is given of 
the available information on inorganic food-stuffs, gaseous exchange, 
respiration, C0 3 -assimilation, nitrogenous and non-nitrogenous 
reserves, and finally of nutrition by organic substances. Here, as 
elsewhere, the references to the work of the various investigators are 
extremely full and will be most useful alike to the advanced student 
and to the specialist. 1 One of the interesting points that is brought 
out is the much greater extent to which algae can avail themselves 
of ammonium compounds and more complicated organic nitrogenous 
substances (even of peptone) than is possible to the higher green 
plants, which mostly depend on nitrates. No doubt this is to some 
extent correlated with the large amount of organic substances, 
produced by the decay of organisms, present in the freshwater 
inhabited by many green algae; but it may be also attributed to 
inheritance from the holozoic and saprophytic flagellates from which 
the green algae at least are descended. 
The fifth chapter deals with the Conditions of Life among 
1 There are no less than 162 references to literature attached to 
this chapter of the work alone. 
