. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 4 F. B. SUMNER AND H. H. COLLINS. some instances enlarged at the end. This tuft was entirely a new growth, since the middle region of the tail is normally covered with very short hair. As the uninjured tail of this rodent terminates in a "pencil" or tuft of longer hairs (Fig. i) the formation of such a tuft at the point of amputation gave the appearance of a restorative process. There are, however, con- siderable points of difference between the normal "pencil" and the secondary one. The former is produce
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 4 F. B. SUMNER AND H. H. COLLINS. some instances enlarged at the end. This tuft was entirely a new growth, since the middle region of the tail is normally covered with very short hair. As the uninjured tail of this rodent terminates in a "pencil" or tuft of longer hairs (Fig. i) the formation of such a tuft at the point of amputation gave the appearance of a restorative process. There are, however, con- siderable points of difference between the normal "pencil" and the secondary one. The former is produced by the gradual elongation of the hair which covers the tail, commencing with the posterior third or half of this member. The restored tuft (Fig. 2) commences much more abruptly, sometimes being. FIG. 2. Tail which has undergone autotomy about midway in its length, and upon which a new terminal tuft of hair has been produced. confined to the end of the stump. Its hairs are much longer than those of the natural pencil, and their pigmentation is conspicuously decreased, being pale gray on the normally black dorsal side. In two instances a small lateral tuft was likewise formed, not far from the end of the stump. In one of these cases, there was found to be an internal injury, corresponding in position to this lateral tuft. The capture of two wild specimens with truncated tails indi- cates that this accident may not be uncommon in nature. There was, of course, no clue to the source of the injury. Both speci- mens had developed terminal tufts, one of these being unusually perfect. The time required for the formation of a new "pencil" has not been definitely noted. We have record of its having arisen within two months, but we also know that more than four months -may be 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 r
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
