. Biology in America. Biology. The Organization of the Egg 195 end of another; two Hydras may be united by either anterior or posterior ends, or one Hydra may be o-rafted onto the side of another. The results differ depending upon the condi- tions of the experiment, and the speeies of Hydra employed; but the general result is that a process of regulation ensues whereby a new animal is formed, similar in size and pro- portion to the normal individual. One of the most interest- ing results l)earing on the question of predetermination of parts is that obtained by grafting two Hydras by their ante
. Biology in America. Biology. The Organization of the Egg 195 end of another; two Hydras may be united by either anterior or posterior ends, or one Hydra may be o-rafted onto the side of another. The results differ depending upon the condi- tions of the experiment, and the speeies of Hydra employed; but the general result is that a process of regulation ensues whereby a new animal is formed, similar in size and pro- portion to the normal individual. One of the most interest- ing results l)earing on the question of predetermination of parts is that obtained by grafting two Hydras by their anterior ends and then cutting off' the posterior end of one near the graft line. In this case a new head forms on the. Four-Legged Tadpoles Produced by transplanting the limbs from one tadpole to anotlicr. After Harrison, "Journal of Experimental Zoology,'' Vol. 4. (originally) posterior end of the graft, where a head, in the ordinary course of events would never develop. Some of the most interesting grafting work of recent years has been done by Harrison, in connection with studies on the developing nerve fiber. Two positions have been held on this question—one, that the axone of the nerve cell, the conducting part of the nerve fiber, arose in situ from surrounding cells; the other, that the axone was an outgrowth from the nerve cell itself. The latter view appears to have been definitely established by Harrison. Our interest here however centers primarily upon certain secondary results of Harrison's work rather than upon the question of nerve fiber development. In these experiments Harrison has shown that limb buds can be transplanted from one tadpole to another, the tail of one. 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 Young, R. T. (Robert Thompson), b. 1874. Boston, R. G. Badger
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