Studies In Animal Behavior

Paperback | February 2, 2012

bySamuel Jackson Holmes

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1916. Excerpt: ... THE REVERSAL OF TROPISMS /NE very prevalent and noteworthy peculiarity -'of the tropic movements of animals and plants is the phenomenon of reversal. The same organism may show a positive or a negative reaction to temperature, light, gravity or the electric current according to the strength of the stimulus, the organism's own condition or the coincident influence of other agencies. Through this power of reversal behavior is rendered more plastic. Granting that the tropisms are involuntary reactions to external stimuli, the fact that the organism may go either toward or away from a stimulus according to how it is influenced by various internal and external conditions makes its behavior much more varied, and affords an opportunity for a closer adaptation to the numerous environmental agencies that affect it. It, is not to be inferred that all reversals of tropisms are adapted to meet some organic need. In many cases nature does not seem to have conferred upon the organism any power of reversal whatsoever. The pomace-fly Drosophila is positively phototactic in very strong light, but Carpenter has shown that when an intensity of 480 candle power is 93 reached the movements of the insect are no longer definitely controlled. The flies tumble and whirl about in an irregular way, but in no case do they show a negative reaction. There are other cases in which the power of reversal occurs, but where it is not brought into play when it would seem to be most needed. The large terrestrial amphipod or sand flea Talorchestia longicornis is ordinarily positive in its reactions to light. When first exposed, especially if it is wet or cold, it may show a vacillating tendency toward the negative reaction, but in strong light, especially in a higher temperature, it becomes s...

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1916. Excerpt: ... THE REVERSAL OF TROPISMS /NE very prevalent and noteworthy peculiarity -'of the tropic movements of animals and plants is the ...

Format:PaperbackDimensions:60 pages, 9.69 × 7.44 × 0.12 inPublished:February 2, 2012Publisher:General Books LLCLanguage:English

The following ISBNs are associated with this title:

ISBN - 10:0217997619

ISBN - 13:9780217997614

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