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. 1907 Excerpt: ...which, one would suppose from their structure, were capable of much better image-formation than those of any of the other forms so far employed; but the results of the experiments fail to confirm this point. The explanation is probably to be looked for in the fact that on account of the influence of other factors the ...
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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. 1907 Excerpt: ...which, one would suppose from their structure, were capable of much better image-formation than those of any of the other forms so far employed; but the results of the experiments fail to confirm this point. The explanation is probably to be looked for in the fact that on account of the influence of other factors the reactions to light are masked, and probably to a certain extent inhibited. 6. Mourning-cloak Butterfly ( Vanessa antiopa Linn.). The work of Parker (:03) on Vanessa naturally suggested that animal as a favorable subject for these experiments. The following conclusions reached by Parker (: 03, p. 467) are of importance in the present connection: "3. V. antiopa creeps and flies toward a source of light, that is, it is positively phototropic in its locomotor responses. "4. Its positive phototropism occurs with lights varying in intensity from 2 candle-power at 2 meters distance (0.5 candle-meter), t) 250 candle-power at 2 meters distance (62.5 candle-meters).... "10. V. antiopa does not discriminate between lights of greater oi less intensity provided they are all of at least moderate intensity and of approximately equal size. "11. V. antiopa does discriminate between light derived from a large luminous area and that from a small one, even when the light from these two sources is of equal intensity as it falls on the animal. These butterflies usually fly toward the larger areas of light." It will be seen that Parker had already concluded what might be expected to result from experiments on these butterflies under the conditions of the present investigation. His conclusions were based in large part upon observations in the field, supplemented by a number of experiments conducted in the laboratory. These, while they seemed t...
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Add this copy of An Experimental Study of the Image-Forming Powers of to cart. $38.69, good condition, Sold by Bonita rated 4.0 out of 5 stars, ships from Newport Coast, CA, UNITED STATES, published 2011 by Nabu Press.
