Proceedings of the International Congress of Zoology Volume 7, PT. 1907 (Paperback)

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. 1912 edition. Excerpt: ... stimuli that manifest their actual physiological state to their fellows. Now these two qualities are certainly present in Protozoa. Jennings found that even Amreba passes, by the action of stimuli, into distinct physiological states of typically different irritability. For instance the stimulus of mechanical touch is answered differently when interlocked with the simultaneous stimulus of creeping on the ground or with that of free-swimming. And in higher Protozoa he found the same capacity still more developed. On the other hand there is no doubt that the constitution of a protozoan would allow, if desired, the production of manifesting stimuli. Of course they cannot produce sounds or specialized movements as the social insects do; and if they could it would be of no use, as the task to take up acoustic, optic, or complicated mechanic stimuli would be far beyond the powers of their fellow-protozoa. But also chemicals are suitable means of communication. It would not at all be asking too much, if we assume that certain Protozoa secrete in every one of their physiological states a trace of some special chemical into the surrounding water. And as the fitness to answer chemical irritation is the simplest sort of all and highly developed among Protozoa, such specialized secretions could easily serve as adequate stimuli, which induce other individuals to correspondingly varied behavior. Well, then, we find Protozoa endowed with qualities that would enable them to become social, and group as a harmonious-equipoten-tial system after a given proportion. Elastomeres are, as we said above, descendants of Protozoa, and their behavior cannot only but ought to be essentially equal to the behavior of those. Thus we are, until the contrary be proved, simply...