No. 64Y] AUTOPHORIC TRANSPLANTATION 551 



ceive the organism as an engineer mending his own body ? 

 "When the visceral mass of Antedon is not replaced, a new 

 sac is regenerated by the creature. As in all cases of 

 regeneration known to me, it is nothing else than an ac- 

 celeration of growth going on normally at slower rate, 

 but in the same direction and sense. From this theoreti- 

 cal standpoint, which has been proved to be correct over- 

 and over again, we can be satisfied that there are growing 

 forces in the Antedon sufficient to ensure the attachment 

 of the new visceral sac. 



We have heard that in higher animals regeneration is 

 not as ready to supply lost parts, and as soon as growth 

 ceases, for instance in the imago of insects, the faculty 

 of restoring missing limbs is lost. But a certain degree 

 of repair has been noticed and experimentally tested even 

 here, for instance the closing of holes pricked in the in- 

 tegument of beetles, and even the resprouting "of torn- 

 out wings as mere skin duplicatures. In vertebrates a 

 good deal of physiological regeneration is always going 

 on in the tissues, and transplanted pieces of living tissue 

 often become attached in a short time by connective tissue 

 and blood vessels growing over and into them. Will ex- 

 change of organs lead under certain conditions to their 

 functional restoration also in such animals as these? 

 The first condition must be the possibility of removing 

 the part to be replaced always in the same place and man- 

 ner, so as to be sure that it wiH comprise just the same 

 material and fit in again in the corresponding place of 

 the new host. Planes of preformed breakage would an- 

 swer best to this condition, but they are generally pre- 

 cluded by the second condition that must be fulfilled, 

 namely retention of the implanted organ by the own forces 

 of the recipient. Such forces may be divided into three 

 groups : first, the natural friction of a mass pressed into 

 a socket, also aided by atmospheric pressure; secondly, 

 the active aid of muscle and nerve clutching the im- 

 planted organ and preventing it from falling out of its 

 place; thirdly, the clotting of the body fluids, gluing, as 



