182 Drew .— The Reproduction and early Development of 
The cultures were made in glass jars of about 5 °o c.c. capacity. These 
were first thoroughly washed with boiling water, dried, and then filled with 
the culture solution, after which they were inoculated with pieces of the 
reproductive areas, of about one square inch in size. The jars were 
covered with a sheet of glass, and placed in a window with a north light. 
The room temperature varied between 13 0 C. and 17 0 C. 
In the case of Laminaria saccharina , considerable difficulty was 
caused by the plentiful growth of yeasts and Bacteria, which was possibly 
favoured by the presence of mannite in the thallus. Accordingly it was 
found advisable to pipette off some of the flagellated gametes, and to make 
subcultures. By this means cultures that appeared free from all bacterial 
growth were eventually obtained. 
In the case of Laminaria digitata , it was found possible to rear the 
young plants in the original jars without making subcultures, but the 
results were complicated by the free growth of various species of Ectocarpus 
and diatoms, which apparently were always introduced with portions of the 
reproductive areas. By continuous washing and brushing in sterile water, 
in the manner described, it was found possible to reduce the amount of this 
growth, but it was never entirely eliminated. Where a free growth of 
Ectocarpus occurred, it was found that most of the young Ectocarpus plants 
of the second generation floated on the surface film of the water, and, pro¬ 
vided the jar had not been shaken, they could be skimmed oft and so 
removed. 
On several occasions I observed the ‘swarming’ conjugation of the 
gametes of various species of Ectocarpus. 
When the young Laminaria plants had grown about one-quarter of an 
inch long, it was usually found advisable to empty out the culture solution 
and smash the jars, having first marked them out in small squares with 
a diamond. The small pieces of glass with the attached plants were then 
placed in glass dishes filled with the same solution. By this means over¬ 
crowding was avoided, and fresh growths of Ectocarpus that developed 
in the later stages of impure cultures could be conveniently removed with¬ 
out disturbing the young L.aminaria plants. Experiments conducted 
in Petri dishes were unsuccessful, although some plants were grown from 
the gametes in small flasks holding 50 c.c. in which the depth of the solution 
was about two inches. 
At first the various stages of growth were observed in the cultures by 
pipetting out drops from the region of the focus of the light (away from the 
source of light in a round jar), where the liquid appeared faintly cloudy 
from the presence of the gametes : in the later stages it was necessary 
to make scrapings from the sides of the jars. Pipettes that had been 
sterilized with boiling water were always used. 
