6jo Blackman .— The Primitive Algae 
between two opposed methods of nutrition, the algal and the 
fungal, just as it may happen to be well fed or not. 
Bohlin (’9 7a) has described a similar case of alternative 
nutrition for Chloramoeba which belongs to a different class 
of Flagellates, so that in the hypothetical transition from 
the colourless Protomastigina to the Chlamydomonads, the 
necessity for developing chlorophyll is not a serious difficulty, 
in the light of these phenomena. 
Just as green organisms occur among the Flagellata so 
colourless forms are found among the lower Algae. There 
should be really no more objection to letting such colourless 
forms take their place in the respective families to which a 
consensus of their characteristics entitles them, than is made 
as to the position of the chlorophyll-free Flowering Plants. 
Chlamydomonas possesses one species, Chi. hyalina , which 
is, apparently, characteristically colourless and saprophytic. 
Further, related to Chlamydomonas , there exists a small 
group of colourless organisms of which Polytoma uvella is the 
best known. These have been carefully monographed by 
France (’94). They have the cell-structure of the Chlamydo- 
monad type and starch is found in the cells, but they have 
a thick or thin out-standing wall. They divide by transverse 
or oblique divisions into groups of four or eight daughter-cells, 
usually while in the motile stage. Conjugation of gametes (in¬ 
distinguishable from vegetative cells) has been observed. This 
group has thus all the critical characters of the Chlamydo¬ 
monads except the green colour. Early observers of course 
classed them as animals. Dangeard (’88) proved that their 
nutrition was saprophytic and that their cell-wall prevented 
any ingestion of solid particles. It seems clear that they form 
a little family of which all the forms are saprophytic, and that 
they have probably evolved from some one green organism of 
the Chlamydomonad type. This necessitates their being 
placed as a sub-family in the Volvocaceae. They show certain 
resemblances to a special group of colourless Flagellates, and 
it is a theoretical possibility that a saprophytic organism of 
preponderating plant-characters might be evolved from a 
