140 PHOTO-MICROGRAPHS. 
of the protoplasmic contents of the two cells. 
The result of this conjugation (“fertilization ’’) 
is that a seed is formed containing an embryo 
plant, which, when suitably placed, develops into 
a new individual like the parent form. 
The propagation of higher plants by cuttings 
may be compared to the mode of multiplication by 
binary division seen in our figure. 
The life-history of some unicellular Algee also 
includes a phase in which the little plant, instead 
of quietly remaining in one place and devoting 
itself to the business of raising as large a family as 
possible, assumes a motile condition and leads a vaga- 
bond life for a time. 
This is especially well seen in Protococcus, the 
genus to which the red snow-plant belongs, and 
one species of which, in the “ still” condition, is 
probably represented in our figure. 
Dr. Carpenter says: — 
“When the ordinary self-division of the ¢ still’ 
cell into two segments has been repeated four 
times, so as to produce sixteen cells, and sometimes 
at an earlier period, the new cells thus produced 
assume the ‘motile’ condition, being liberated be- 
fore the development of the cellulose envelope, 
and becoming furnished with two long vibratile 
flagella, which seem to be extensions of the colorless 
protoplasm-layer that accumulates at their base, so 
as to form a sort of transparent beak. In this con- 
dition it seems obvious that the colorless proto- 
plasm is more developed relatively to the coloring 
matter than it is in the ‘still’ cells; and it usually 
