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IN VEGETABLE BIOLOGY. 247 
good enough to see by ; it was then examined, uncovered, with a 
Hartnack's No. 7 objective, the time taken by a plastid or group 
of plastids in the centre of the stream to pass over a diameter of 
the field of view being rapidly noted. It only remained then 
to repeat the observation as often as necessary. The following 
were the chief results obtained with Chara vulgaris. 
No. III. 
(Specimen placed in darkness August 10th: examined 
September 10th.) 
Time. d 
4.30 P.M. ......... 40 seconds. 
4.32 P.M. ......... 30 seconds. 
4.35 PM. ......... 15 seconds*. 
4.37 P.M. ......... 12 seconds. 
4.40 P.M. ......... 10 seconds. 
No further increase of velocity occurred. 
Temperature of dark cupboard 68° F.; of room 69°-69°5 F. 
No. IV. 
(A month’s darkness as before; temperature of cupboard and 
room the same within a fraction of a degree.) 
me. | emis 
5.27 P.M. ......... 65 seconds. 
5.32 PM. ......... 20 seconds. 
5.85 P.M. ......... 15 seconds. 
5.40 p.m. m 12 econds. 
Aiter which there was no further increase. 
* Immediately before noting this the blind was drawn up, causing great 
improvement in the light. 
x2 
