The Journal of experimental zoology . responsible. Throughout the course of the experiment it wasnoted that the small protruding part on the left side was veryfrequently and closely attached to the substratum, z. e., it was used inmuch the same manner as a tail, doubtless a consequence of its formand relation to the substratum during movement. But the attach-ment of this part was usually followed or accompanied by theattachment of the other parts of the lateral margins in this regionof the body on both sides. This method of use of the parts must 264 C. M. Child. retard or prevent the decrease
The Journal of experimental zoology . responsible. Throughout the course of the experiment it wasnoted that the small protruding part on the left side was veryfrequently and closely attached to the substratum, z. e., it was used inmuch the same manner as a tail, doubtless a consequence of its formand relation to the substratum during movement. But the attach-ment of this part was usually followed or accompanied by theattachment of the other parts of the lateral margins in this regionof the body on both sides. This method of use of the parts must 264 C. M. Child. retard or prevent the decrease in width in this part ot the body toa certain extent, hence the unusual width even in late stages(Fig. 10) of the posterior part of the old tissue. This, ot course,determines the width of the new tissue at the level ot the boundar\-between old and new. Consequently this also is wider than usual(compare Fig. 10 with Fig. 4). This piece was accidentally killed at the stage of Fig. Series j8 (Figs. 11-16). In this series a specimen somewhatsmaller than the preceding was cut transversely near the posteriorend of the phannx (Fig. 11). Figs. 12-16 show the changes inproportion which occurred, Fig. 14 is probably not quite fullyextended. The decrease in width at the posterior end ot the oldpart is marked in Figs. 12-14. Toward the end of the experiment(Figs. 15-16) the change is an almost proportional reduction insize, though with approaching exhaustion there is some relative Studies on Regulation. 265 decrease in length. Fig. 16 represents the specimen ninety-sixdays after section. A few days later it died. Series jg {Figs. ly-z^). The level of section in this series wassome distance posterior to the posterior end of the pharynx(Fig. 17). Figs. 18-23 show the changes in form during onehundred and thirty-six davs. The changes in form of the oldpart are relatively slight in this case as might be expected sinceonly the posterior end is removed and the changes in the d
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Keywords: ., bookauthorwi, bookcentury1900, bookdecade1900, booksubjectzoology
