Sprencer.—On the Fresh-water Algew of New Zealand. 289 
shades of green, from dark olive to emerald, of red, and of blue, from purple 
to sky blue, which we find in the Algm, are very much the prevailing tints of 
the leaves and flowers of aerial plants. And again the reddish and yellow- 
ish brown hues of some Batrachospermea, Lyngbye, Desmids and Diatoms, 
correspond closely with the shades assumed by the leaves of trees, shrubs, 
and herbs, after they have lost their summer verdure, and to which is due 
the picturesqueness of their autumnal foliage. Many Confervoids, which 
when young have green endrochrome, assume in more adult age a yellowish 
or brownish hue, and the analogy between this change and that which 
occurs in the leaves of the oak, the ash, the elm, and other trees, is at least 
both striking and suggestive. 
Many Alge exhibit colours which cannot be referred to autumnal 
influences, or to the effects of age. The prevailing tints among some of the 
Volvocinee and Oscillatoriea have strong points of resemblance with those of 
the flowers of phanerogamous plants. In the latter the diversities of colour 
appear to be connected in some way (of which various explanations have 
been advanced) with the multiplication of the plant, and so we find that the 
flowers are the parts which are most liable to variations of colouration. On 
the other hand, in these simple organisms there is no division into stem, 
leaves, and flowers, almost every portion is concerned in the process of 
teproduction—each filament or frond represents a perfect herb, shrub, or 
tree, and every sporiferous cell is the analogue of a flower. In the pheno- 
gamic class the floral colours are useful as attractions to insects of various 
kinds, which, visiting them for food, carry away the pollen to other flowers, 
and so conduce to their fertilization. Although, so far as I am aware, no 
observations have been made on the subject, is it not something more than 
Possible that the multitudes of Infusoria, Rotatoria, Paramecia, etc., which 
We continually meet with seeking their food amongst the Algw, may assist 
in the same way as insects in conveying antheridial spores” from one plant 
to another ; and that the varying colours of the filaments may be attractive 
to them as those of flowers are to insects; and that thus may be repro- 
— in the subaqueous world some of those phenomena with which we are 
in the aerial ? Should future observation verity this eanjeciare We 
sal see amongst the Alge the exact analogue of the entomophilous fertili- 
zation of flowers, and also be able to understand why the various and 
beautiful tints they exhibit are, to a certain though much less extent, 
Pinan in the filaments and fronds of the fresh-water Algw. — 
the quasion, yt even here 0 subint sees f hve boos aire 
the provision of cilia to the ospores, ‘them to 
oo movements through the water which is their home, ~ 
