246 MR. 8. LE M. MOORE’S STUDIES 
No. II. 
Side of 
Time. Light. Temperature.| marked cell 
traversed in 
Fairly good, heavy | 64?:8 F. | 25 seconds. 
12 o'clock | black clouds just l 
12.15 „ passed over at 
t| 12 o'clock. 
(| Distinct improve-| 6498 F. | 20 seconds. 
| ment in light, 
12.30 „ which was of a 
cre » 4| proximately t e 
» same average in- 
tensity at all three 
periods 
It will be understood that in neither case was the rotation 
allowed to approach its maximum. No. II. shows the equability 
of the stream under continued similarity of illumination. 
The facts upon these tables can be verified without great diffi- 
culty ; but with the Characee it is different. The slowing of 
the protoplasmic stream in this group on withdrawal of light was 
studied half a century ago by Dutrochet *, who found that in 
tbe old parts rotation had become slow by the eighth day, and had 
ceased by the sixteenth t; while in young parts cessation super- 
vened by the twenty-fourth, or at most the twenty-sixth day, by 
which time etiolation had set in. Dutrochet regards the stop- 
page of the stream as an effect of asphyxia; and if his dark 
chamber was a small and hermetically sealed one, this might well 
have been the case. My own experience is different ; for I have 
placed fora month, and even six weeks, in a large dark cupboard 
small pieces of Chara vulgaris, containing at least one uncorti- 
cated internodal cell} with two or more uninjured nodes, without 
causing complete stoppage of the stream, although the diminu- 
tion of its velocity after the above period was very evident. In 
order to bring this diminution clearly into view, the specimen, 
immediately on removal from darkness, was set in water on à 
glass slide, the light employed for this purpose being only just 
* Comptes Rendus, xxxvii. p. 777, and Ann. d. Sc. Nat. ser. 2, ix. 
(1838). 
t By an oversight, “ sixième” is put for “seizième ” in describing this. 
1 Such uncorticated cells are well known as of rare occurrence in Chara. 
