ON BUDDING IN ANIMALS. 15 



buds, until the whole has a remarkably branched condition. The 

 tail of the bud is early formed, and is soon furnished with two long 

 cirri ; indeed, it would seem to be more important than a head. 



The currents through the sponge probably bring this curious 

 Annelid its food, and carry out the free-swimming buds con- 

 taining the eggs. It might be supposed by some that injuries 

 from the sharp spicules of the sponge are connected with the 

 tendency to form branches and buds, but recent experiments by 

 Andrews in other forms show that incisions and similar lesions 

 do not give rise to such growths. One example is thus fitted to 

 take advantage of most of the facilities for accommodation offered 

 by a single sponge, and many would say that the animal had 

 been modified to suit its surroundings ; yet other Syllidce living 

 in sponges are not thus affected. 



A well-marked instance of linear budding (scissiparity) occurs 

 in Filigrana implexa, one of the Serpulids, as described by Sai'S 

 and Huxley. This little Annelid constructs masses of slender 

 calcareous tubes resembling coral. The segments of the parent 

 behind the sixteenth are budded off to form a separate animal, 

 but the head and thorax are new formations. The eggs and 

 other elements occur in the parent-stock, so that the buds con- 

 tain neither eggs nor other elements as in Myrianida and Auto- 

 lysis, though they afterwards acquire them. 



The facility in budding which is possessed by the small 

 Annelids just described is a remarkable feature, since in the 

 Nereids the epitokous or epigamous condition alone occurs. The 

 adults of the latter undergo a kind of metamorphosis, so that 

 with the change in the form of the feet and the development of 

 long swimming-bristles they are enabled to assume a pelagic 

 life, and thus distribute widely the eggs and other elements. 

 Yet it would not appear to be absolutely necessary for such forms 

 to undergo this change in the feet, and acquire the provision of 

 the swimming-bristles, since the well-known Palolo of the South 

 Sea Islands — without any alteration in the shape of its feet — 

 leaves its abode amongst rocks and corals and swims freely in 

 the water. The rarity of the heads of this species amongst the 

 pelagic forms indicates that the posterior region containing the 

 eggs and other elements is thrown off to lead a brief existence 

 amongst the inshore water. 



