photo tonus

phototonus

[foh-tot-n-uhs]
noun Biology.
1.
the normal condition of sensitiveness to light in organisms or their organs.
2.
the irritability exhibited by cytoplasm when exposed to light of a certain intensity.

Origin:
1870–75; photo- + tonus

phototonic [foh-tuh-ton-ik] , adjective
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World English Dictionary
phototonus (fəʊˈtɒtənəs)
 
n
the condition of plants that enables them to respond to the stimulus of light
 
[C19: from photo- + Greek tonostone]
 
phototonic
 
adj

Collins English Dictionary - Complete & Unabridged 10th Edition
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American Heritage
Medical Dictionary

phototonus pho·tot·o·nus (fō-tŏt'n-əs)
n.
The state of being sensitive to or irritated by light.


pho'to·ton'ic (fō'tə-tŏn'ĭk) adj.
The American Heritage® Stedman's Medical Dictionary
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