Wager: Movements of Aquatic Micro-Organisms. 173 
sometimes in all, are pushed out of the way to the posterior 
end of the cell and the organism then lives saprophytically as 
an animal or other non-chlorophyll containing organism. 
If the light conditions again become favourable the chlorophyll 
is brought back into its normal position, and the chlorophyll 
I. 
I. — Euglena, showing: radiating- chloroplasts in the centre, paramylum 
grains, nucleus at posterior end of cell, eye-spot and flagellum at anterior 
end. II.- — Trachelomonas, and III., Phacus, also show a similar structure. 
function being once more resumed, the organism lives as a 
green plant. In both cases an abundant store of food is 
produced in the cell in the form of paramylum grains. 
Under certain conditions the motile state persists, under 
1914 June 1. 
