95 
Br acker. — Observations on Euglena closes. 
slower than that made by the free-swimming forms such as E. viridis. 
Fig. I shows the changes in shape occurring in one specimen of E. deses 
during several minutes’ observation under the microscope. 
Fig. i. 1-5. Euglena deses , showing changes in shape occurring in one individual during several 
minutes’ observation. (Mag. 400 times.) 
Daily Movements of E. deses dependent on External 
Factors. 
A series of observations were made on the Avon banks between dawn 
and sunset with a view to investigating the times of the daily movements 
of Euglena. 
At dawn no Euglenae are Visible on the surface of the mud, but from 
readings taken in October, December, April, and May the green colour 
begins to appear about one to two hours after sunrise. 
Average 
Time of 
Month. 
Week. 
lime of 
Appearance 
Sunrise. 
of Euglenae. 
October 
8 th- 1 5 th 
6.12 
7-30 
December 
3rd-9th 
7-45 
9.0 
April 
23rd-29th 
4-37 
6.30 
May 
1 4th- 20th 
4-3 
6.0 
As the light becomes brighter and the temperature increases the mud 
becomes correspondingly greener, until about midday the surface is very 
green indeed. The organisms remain thus exposed until the light begins to 
fade in the evening, when they once more disappear from view and burrow 
down into the mud. Readings were taken in the same months for the time 
of disappearance of the organism, which is shown to be less than half an 
hour before sunset. 
Month. 
Week. 
Average 
Time of 
Stmset. 
Time of 
Disappearance . 
October 
8th- 1 5th 
5-*5 
5.0 
December 
3rd~9th 
3-49 
3.30 
April 
2 3rd- 2 9th 
7.18 
7 -° 
May 
14 th- 20th 
7.40 
7-30 
