30 
ZOOLOGY: W. H. COLE 
Proc. N. a. S. 
The first grafts consisted of tail skin placed over the eye. Sixty-six 
per cent of these showed an adjustment whereby a small part of the graft 
was absorbed in a manner which tended to restore vision. When back 
skin was used, no such absorption occurred. Skin from the tail or back, 
grafted on other parts of the body, persisted indefinitely. However, when 
tail skin was grafted over hemispheres of glass or celloidin with radii 
equal to the radius of the eyeball, absorption occurred. The process in 
these grafts over "artificial eyes" was like that over normal functional 
eyes. Back-skin grafts so placed were not absorbed. As a check experi- 
ment, to determine whether or not the presence of the foreign material 
caused the absorption, other operations were made in which thin plates 
of glass cut from the ordinary cover-slip were used instead of the hemis- 
pheres. Such grafts were not absorbed, proving that the foreign material 
was not the cause of absorption. 
From a study of the transplants, it was concluded that the curvature 
of the eyeball and of the artificial eye is the cause of absorption of tail- 
skin grafts. The plastic tail skin yields to the tension produced by the 
curvature and adjusts itself. In the majority of cases, this adjustment 
by absorption of tissue incidentally restores vision. It always ceases as 
soon as the tension is relieved. When the graft is very thick or is unusually 
well attached to the host, no adjustment is possible. Nor is it possible 
in back-skin grafts, because of their more compact structure. 
The proliferation of new tissue by the transplants was limited to the 
tail-skin grafts. In some cases miniature tail tips were formed, while 
in others irregular proliferation predominated. This latter type is called 
"amorphic regeneration." The original anterior end, as well as the pos- 
terior end, of the graft is able to produce a new notochord and nerve cord 
in the regenerated tissue. It was found that the absence of light hastens 
the proliferation period by about nine days, and slightly increases the rate 
of proliferation. "Dark" grafts regularly showed amorphic regeneration. 
Following the period of proliferation, all grafts entered a state of equi- 
librium. In none of the grafts taken from the back or the belly was pro- 
liferation observed. 
The conclusion is reached that no functional regulation of skin grafts 
over the eyes occurs. The adjustment which does take place is purely 
mechanical and its relation to the visual function is quite incidental. 
The lack of correlative regulation is probably the result of the high state 
of differentiation and specificity attained by the eye and the skin. 
2. When integument from the tail, belly, or back is transplanted to 
another region on the same animal (auto-transplant), it preserves its 
characteristic appearance and produces new tissue of its own kind indefi- 
nitely. An homoio-transplant (from another individual not closely re- 
lated) preserves its integrity only temporarily, being ultimately replaced 
