. Senescence and rejuvenescence. Age; Reproduction. THE KECONSTITUTIOX OF ISOLATED PIECES "3. W character of the head departs from normal. In pieces of the same length and from the same region the size of the head and the length of the pharyngeal and prepharyn- geal region are less in teratophthahnic and teratomorphic than in normal animals and less in anophthalmia than in teratomorphic or teratophthahnic forms. Between the teratophthahnic and teratomorphic forms the differences in this respect are not very great except when opposite extremes of the two types are compared. That the produc
. Senescence and rejuvenescence. Age; Reproduction. THE KECONSTITUTIOX OF ISOLATED PIECES "3. W character of the head departs from normal. In pieces of the same length and from the same region the size of the head and the length of the pharyngeal and prepharyn- geal region are less in teratophthahnic and teratomorphic than in normal animals and less in anophthalmia than in teratomorphic or teratophthahnic forms. Between the teratophthahnic and teratomorphic forms the differences in this respect are not very great except when opposite extremes of the two types are compared. That the production of a normal or nearly normal animal from a piece requires more energy than the production of a head- less form is indicated by the fact that a much greater amount of reduction occurs in the former than in the latter case. Moreover, in a given lot of pieces it is possible by means of external conditions such as temperature, low concentrations of narcotics, etc., whose effect is primarily quantitative rather than quahtative, to determine experimentally within wide limits which of the five forms shall be pro- duced (ChUd, 'lib, '12b). Experiments of this kind have demonstrated that aU four forms from the teratophthahnic to the headless are what might be called sub- normal, , they are due to various degrees of retardation or inhibition of the dynamic processes (Child, '116, '14a, '146). .\nd, finally, after their development is com- pleted, the normal head shows in general a higher susceptibility than the teratoph- thahnic and teratomorphic, and these a higher susceptibihty than the anophthabnic. Fig. 24.—Body-outline of Planaria dorotocephala, indicating levels of Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Child, Charles Manning, 1869-1954. Chicago, Ill. , The University of Chicago Pre
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectreproduction, bookyea
