. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. THE ATTACHMENT OF BARNACLE CYPRIDS 49 attachment response to a contact stimulus. The possibility of a tropism is not supported by the contrast experiments. In the light of the above conclusions it may be interesting to recall the experi- ments of Schallek (1943) and Whitney (1941) who maintain that directional light is not to any great degree present under natural aquatic conditions but that condi- tions of diffuse light almost invariably predominate. This diffuse light is a natu- rally occurring phenomenon, whereas light fr
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. THE ATTACHMENT OF BARNACLE CYPRIDS 49 attachment response to a contact stimulus. The possibility of a tropism is not supported by the contrast experiments. In the light of the above conclusions it may be interesting to recall the experi- ments of Schallek (1943) and Whitney (1941) who maintain that directional light is not to any great degree present under natural aquatic conditions but that condi- tions of diffuse light almost invariably predominate. This diffuse light is a natu- rally occurring phenomenon, whereas light from any one direction may not pre- dominate sufficiently for a tropism to occur. SUMMARY 1. Experiments were conducted to determine the effect of contrasting surround- ings upon the frequency of attachment of Balanns cbnrncits larvae to opaque black and opal glass collecting surfaces. Further experiments were carried out to determine to what extent the number of attachments of transparent collectors was influenced by black and opal backgrounds placed at varying distances. 2. Greater numbers of attachments occurred upon the under side of horizontal rather than vertical, and upon black rather than opal collectors, thus confirming the observations of previous authors. 3. No correlation was found between the degree of contrast shown in the collector and surroundings, and the frequency of attachments. 4. Both black and opal surfaces were found to increase frequency of attach- ment when placed behind transparent collectors up to distances of six inches. 5. A definite dependence was found to exist between the frequency of attach- ment and a decrease in the intensity of general illumination in the area immediately beneath horizontal opal collectors. Similarly, the influence of movable back- grounds appeared to be in the nature of a shadow effect. It is suggested that "shading" acts as a stimulus which brings about favorable physiological conditions for the subsequent attachmen
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
