REGENERATION AND BUDDING 149 



REGENERATION AND BUDDING 



In several groups of animals a process of budding takes place 

 that presents certain features not unlike those of self-division. It 

 is difficult, in fact, to draw a sharp line between budding and self- 

 division, and although several writers have attempted to make a dis- 

 tinction between the two processes, it cannot be said that their 

 definitions have been entirely successful. It is possible to make a 

 distinction in certain cases that may be adopted as typical, but the 

 same differences may not suffice in other cases. For instance, the 

 development of a new individual at the side of the body of hydra is a 

 typical example of budding, while the breaking up of lumbriculus or of 

 a planarian into pieces that form new individuals is a typical example 

 of division. In a general way the difference in the two processes 

 involves the idea that a bud begins as a small part of the parent ani- 

 mal, and increases in size until it attains a typical form. It may 

 remain permanently connected with the parent, or be separated off. 

 By division we mean the breaking up of an organism into two or 

 more pieces that become new individuals, the sum-total of the 

 products of the division representing the original organism. Von 

 Kennel first sharply formulated this distinction, and it has been also 

 supported by von Wagner, who has attempted to make the distinc- 

 tion a hard and fast one ; 1 but as von Bock has pointed out, there 

 are forms like pyrosoma and salpa in which the non-sexual method 

 of propagation partakes of both peculiarities, and in Syl/is ramosa the 

 individuals appear to bud from the sides, while in other annelids a 

 process of division takes place. Von Bock assumes, therefore, as 

 more probable, that budding and self-division are only different phe- 

 nomena of the same fundamental process. It might be better, I 

 think, to go even further in order to clear this statement from a pos- 

 sible historical implication, and state only that the two processes 

 involve some of the same factors. 



Budding occurs in several groups of the animal kingdom. There 

 are numerous cases in the protozoa, such, for instance, as that in 

 noctiluca. In the sponges buds are formed that go to build up a col- 

 ony in most instances. In the coelenterates cases of lateral budding are 

 found in nearly all the main groups, and in one and the same indi- 

 vidual, as in the scyphistoma of aurelia, in fact both budding and 

 division occur. In the polyzoa, in the ascidians, and in cephalodiscus 

 lateral budding takes place. In the rhabdocoel turbellarians, and in 

 some of the annelids, we find chains of new individuals produced by 

 a process that is often spoken of as budding. It is convenient, how- 

 ever, to distinguish these cases of axial budding from those of lateral 



1 Except for the protozoa. 



