The Cell-Lineage and Early Larval Development of Fiona Marina, a Nudibranchiate Mollusk

The Cell-Lineage and Early Larval Development of Fiona Marina, a Nudibranchiate Mollusk

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1905 edition. Excerpt: ...continuing as long as certain conditions continue, increasing in effectivenessas the conditions causing it increase in intensity, and ceasing when the conditionscausing it cease, maintaining the organism throughout in certain relations with the source of stimulation. Altogether, I believe that the following admission must be made. If we consider the reaction of Paramecium a reflex, it is because we are convinced beforehand that such an organism can show only reflexes. If the actions of Paramecium did belong to some higher type of behavior, there could be little objective evidence of this, beyond what we already have. In Paramecium the reaction has not been shown to be modifiable by previous experience, so that from this criterion the behavior retains the characteristics of a reflex. But in a close relative, Stentor, such modification by experience has been demonstrated (JENNINGS, I902), so that it may be presumed that technical difficulties alone have thus far prevented our observing it in Paramecium. The effectiveness of the method of reacting by "trial and error" that we have described above for Paramecium depends upon the power of discrimination of the reacting organism. By "discrimination" of stimuli we mean, in an objective study of behavior, that the organism reacts differently to the different stimuli in question. In this sense Paramecium discriminates acids from alkalies and salts, and these again from sugar. Furthermore, it discriminates different strengths of solution, reacting differently, for example, with relation to weak and to strong acids. On the other hand, it does not effectively discriminate different acid substances, save in so far as one is stronger than another. Thus it swims into weak carbonic...
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Product details

  • Paperback | 100 pages
  • 189 x 246 x 5mm | 195g
  • United States
  • English
  • Illustrations, black and white
  • 1236749316
  • 9781236749314