1893.] NATURAL SCIENCES OF PHILADELPHIA. 77 



There may also be a kinship detected in the tendency of Hydrozoa 

 and Scyphozoa to reproduce themselves in this way, especially the 

 sedentary or colonial forms. The tendency of star-fishes to bud out 

 branches from their arms is another illustration of the same thing, 

 and it has been recently shown that under exceptional conditions 

 the point where an arm of a star-fish is budded off may mark the 

 point near where a new mouth and a full complement of arms will 

 appear so as to develop a complete new individual. 



As we rise in the scale of organization, this tendency to regener- 

 ate lost parts becomes more and more restricted to the reproduction 

 of peripheral parts only, but the tendency to produce monstrosities 

 in the shape of more or less completely fused embryos, due to dis- 

 turbances of development, remains in full force. Not only is this the 

 fact, but I also believe that I have indisputable evidence that an 

 embryo may undergo partial development within the uterus of a 

 mammal, when it will be arrested and actual histolysis with conse- 

 quent destruction and absorption of the embryo takes place. More 

 remarkable still is the conclusion reached bv von Jherino: that 

 certain Armadilloes normally produce several young from a single 

 fertilized ovum. His view being that in no other way can we 

 explain the envelopment of the entire litter of young of some of the 

 species of these animals in a common chorion. In this opinion, I 

 take it, von Jhering has the support of the opinion of authorities 

 as eminent as von Kolliker and H. Milne-Edwards. 



When certain of the vertebrates such as fishes, batrachians and 

 reptiles are injured after adolescence is reached, they retain to a 

 limited degree the power to reproduce lost parts. Not only do they 

 possess this power, but they tend to reproduce such parts in dupli- 

 cate, that is, the peripheral part is reproduced double, and as if 

 diverging from the point of mutilation. An instance of this that I 

 recall is the case of a fine Amieva, in the collection of the 

 Academy of Natural Sciences of Philadelphia, had its tail torn off, 

 and from the point where the tail was removed two new tails were 

 being produced. Other equally striking instances are the toes of 

 Salamanders that have been injured. The Axolotl and its kindred, 

 the species of Amblystoma, do the sarae thing when the toes are 

 injured or nibbled off by fishes ; the tendency is to reproduce them 

 in duplicate, or even in triplicate. The same thing happens when 

 a fin-ray is injured or torn out in the fins of a Malacopterygian fish : 

 ■the actinotrichia tend to be reproduced in manifold and radiate 



