CHAPTER I. 
Chlamydomonas variabilis Dangeard. 
-8 1. The culture-method used and the determination of 
the Alga obtained. 
For my experiments Ï used an unicellular motile Alga, 
Chlamydomonas variabilis Dangeard. For representatives 
of the Chlamydomonas and of some narrowly related 
Algae there is a suitable culture-method. The latter is 
stipulated by Jacobsen (1910) In a vessel of glass one 
puts some fibroïn in water. We moculate with a great 
quantity of good garden-ground. After bacteria have 
affected the fibroin at first, the Alga gradually begins to 
develop itself. With a favourable course of events the 
whole fluid becomes green in course of time. If once a 
good culture has been obtained, we can soon acquire a 
new culture by inoculating in water with fibroïn and 
sterilized ground. After Î had been using fibroïn for some 
time, | added, according to Buder's advice, dried white 
of eggs. By this the time, necessary to develop a culture, 
is considerably shortened. Sometimes we obtain very dense 
cultures, in other cases, however, it is much more difficult 
to have good material at our disposal. This is especially 
the case in autumn and in the beginning of winter. 
Of all cultures a part was set aside and fixed with 
formaline. The determination of the material proved that 
I had been working almost exclusively with the same 
