LIFE HISTORIES OF ALG^E 237 
and other marine animals. In 1913 it was successfully 
accomplished by Over ton with the eggs of Fucus. The 
eggs were dipped for about a minute, or a minute and a 
half to two minutes, in a mixture of 50 cc. of sea-water 
plus 3 cc. of a very weak solution of acetic, butyric, or 
other fatty acid, and then transferred to normal sea- 
water. This treatment caused the formation of the fertili- 
zation-membrane, quite as in natural fertilization by the 
sperm. If, after the formation of the membrane, the eggs 
are placed for 30 minutes in hypertonic sea-water (50 cc. 
of normal sea-water plus 8 to 10 cc. of a weak solution of 
sodium chloride (common salt), or potassium chloride), 
and then back into normal sea-water, the eggs begin to 
divide and continue to develop into young plants. The 
question as to the chromosome number in the cells of 
plants formed by artificial fertilization is of very great 
interest, but has not yet been investigated. 
218. Germination of the Oosperm. After either natural 
or artificial fertilization the young zygote begins at once 
to divide, without any period of rest. Of the two cells 
formed by the first division, one gives rise to the hold-fast 
organ, by which the new plant is attached to the rocks, 
while the other develops into the main body of the plant, 
which resembles the parent plant in all external characters 
(Fig. 175). 
219. Reduction. As always in normal fertilization, the 
nucleus of the oosperm is diploid, and the Ascophyllum 
plant that develops from it is also diploid. It is therefore 
the sporophytic generation. At the end of the first two 
nuclear divisions of the spermagonia and oogonia, re- 
duction has been accomplished, and the four nuclei that 
result are haploid. They therefore belong to the haploid 
