320 



ANIMAL DEVELOPMENT 



other has to swim away, attach itself to some firm body, and 

 grow a new stalk. In some relatives of the Bell- Animalcule, 

 and certain other Protozoa, colonies are formed by continuous 

 fission, the products remaining united. 



Budding (Gemmation). This differs markedly from fission, 

 because the parent Animalcule does not lose its individuality. 

 One or more projections grow out from its body and receive a 

 part of the original nucleus. These buds then become narrower 

 and narrower at their attached ends, until at last they drop off, 



after which they gradually acquire 

 the size and shape of the parent 

 form from which they sprang. 

 Comparatively simple illustrations 

 of budding are afforded by the 

 members of a curious group of 

 Animalcules (Suctoria), which are 

 devoid of mouth, but possess a 

 number of slender outgrowths 

 from the body that serve as a 

 means of catching such prey as 

 other Animalcules, and sucking 

 the juices of these when secured. 

 A stalked member of this 



, . ,. 



grOUp {hpkelota gemmipaTO) IS 



J * .C O 1~ * I. 1. 



branching nucleus; c, a detached bud. D-F, Internal depicted If! tig. 645, WHICH SHOWS 



f bUClS g rOWln g Ut fr m 

 , and receiving twigfS from 

 ' 1 i 1 r 1 



the much-branched nucleus 01 the 



A detached bud at a later stage is also represented, 

 and it will be seen that this has begun to develop the curious 

 suctorial projections that are characteristic of the group. 



In some cases there may be an internal cavity (brood-cavity), 

 within which a bud is formed. This is exemplified by a stalked 

 Animalcule (Tokophrya quadripartata, fig. 845), belonging to the 

 same group as the form last mentioned. Here the bud is pro- 

 vided with a broad ciliated girdle, and, when mature, squeezes out 

 to the exterior through an opening present in the brood-cavity. 

 After swimming about for some time by means of its cilia, the 

 bud settles down, attaches itself to some firm body, loses its cilia, 

 and develops the stalk and suctorial structures which are char- 



Fig. 845. Budding Animalcules, enlarged 



A-c, External budding of Ephelota: A, body of an 

 adult (the stalk is cut short); B, an individual produc- 

 ing buds, each containing an outgrowth from the 



mature bud lying in the brood-cavity; F, free-swim- 

 ming bud. 



parent. 



