ON BUDDING IN ANIMALS. 5 



umbrella or disk (Hybocodon and Sarsia prolifera) . Buds are 

 also seen in Hydra tuba, the primary condition in the develop- 

 ment of the scyphomedusas such as Aurelia. The whole group of 

 the Corals, again, is characterized by free budding and branching, 

 so that the outlines of many are beautifully arborescent, for, as 

 a rule, the new growths remain attached to the old. In Fungia, 

 however, the young Coral is budded from a fixed axis or stock, 

 and subsequently leads an independent existence. 



Why, it may be asked, is budding so prominent in the 

 Ccelenterates ? Is it due to the fact that the so-called " somatic 

 cells " of Weismann still retain a certain capacity for renewing 

 the species, so that a small number of them are able to give rise 

 to a new organism in the form of a bud ? But some of these 

 cells likewise develop the ordinary differentiated elements for 

 increase, so that their functions would seem to be twofold. 

 Moreover, in forming the Medusa-bud, it is possible that besides 

 the " somatic cells " from the axis (blastostyle) the reproductive 

 cells may be introduced into the developing bud, and give rise 

 at a subsequent stage to the eggs or other elements characteristic 

 of each. 



The plant-like form of the chief examples of the group, 

 moreover, is most favourable for continuous budding, so that 

 by such means, for instance in the hydroid zoophytes, the 

 capsules containing the eggs or other elements are greatly in- 

 creased in number on any individual stock. Such certainly 

 would be an advantage to the species. In the same way in 

 other forms the swimming jellies or medusoids which are budded 

 off to develop the eggs or other elements give the species enormous 

 powers of distribution — powers which the mere discharge of eggs 

 or larvae on the site of the parent-stock could scarcely accom- 

 plish. But though these little jelly-fishes carry the eggs to dis- 

 tant regions, and mingle with others reared in diverse localities, 

 it has to be shown that those which have this means of dispersion 

 are greatly more abundant than those which do not possess 

 them. Certainly such rapidly growing forms as Obelia, with 

 their swimming buds, would appear to be more plentiful in some 

 localities than Sertularians, which develop directly, and which 

 would seem to be the more primitive type, since the distribution 

 of the eggs by means of the Medusa-bud is a more complex 



