480 The Botanical Gazette. [December, 
. To variation in the intensity of light. Called ‘‘sleep 
movements;” ‘‘nyctitropic movements;” ‘‘ variation 
movements.” (Pfeffer. 
To variations in temperature. 
To mechanical stimuli. 
To electrical stimuli. 
To chemical stimuli. 
To intensity and direction of light, or para- and diahe- 
liotropism. 
Suggestions on terminology. 
The phrase ‘‘sleep of plants” is, of course, entirely fanci- 
ful. Even as far back as the time of Senebier it was known 
that this Linnean phrase was not scientifically correct, yet it 
has continued in quite frequent use even up to the present 
time. The movements have also been called nyctitropic 
movements, among which Darwin includes the nutation move- 
ments of growing leaves. Even if we confine this term to 
the movements of plants with motor organs, the term is still 
not a good one. Etymologically it means night-turning 
movements; now from the nature of the movements, it 1s 
evident that since the leaves assume a different position at 
the approach of day, it would be just as proper to use a term 
meaning day-turning movements. For this reason it seems 
to me that some other term would be better. Since we know 
the real cause of the movements, the gradual variation in the 
intensity of the light, would not a word expressing that be 
.better? For this reason I propose the term photeolic move- 
ments, from the Greek gas meaning light, and aioAos, vart 
able. This term would be only applicable to movements 0 
leaves which have special motor organs, and not to those simi- 
lar movements which are auxotonic. 
One more point in regard to the terminolog 
to me to be of importance that we use terms 
tifically correct. The special organ of motio 
called, ‘‘the motile organ,” or the ‘‘ pulvinus,’ 
same as the ‘‘Gelenkpolstern” of the Germans. is 
on ‘The mechanism of movement in Cucurbita, Vitis a? 
Robinia,” Penhallow® speaks of tendrils as motile organs. he 
can not deny him the right to use this term, for tendrils cer 
tainly are motile organs. Here then is a confusion of a com- 
Vitis and Robinia. 49: 
Q 
SS Qo & 
y, for it seems 
that are scien- 
n is commonly 
’ which is the 
hy enhallow; Mechanism of movement in Cucurbita, 
1886. 
In his paper 
