512 Mr. H. M. Bernard on the 



segmentation to serial budding is singularly apt. No group 

 of animals before or since, excluding perha])s the Protozoa, 

 have shown such marvellous developments of this method of 

 reproduction. The number of successful colony-formations 

 among the Ccelenterates, both stationary and free-swimming, 

 is perfectly bewildering. We have, then, in this power of 

 increase by budding a wealth of possibilities upon which we 

 can safely draw without putting any strain whatever upon 

 our sense of what is probable. 1 go even further, and think 

 it possible to show that free-swimming strings of buds must 

 at one time have existed as a necessary interaction between 

 an organism like the Ccelenterate, capable of budding any- 

 where, and its environment. 



I prefer, then, to go lower down among the Coelenterates 

 than Prof. Sedgwick, lower down either phylogenetically or 

 ontogenetically, for the origin of the Annelids — i. e. to forms 

 either primitive or larval, and before the mesenteries (which, 

 I think, developed as muscular bands drawing and holding in 

 the primitive mouth in order to form an oesophageal infolding"^) 

 appeared. 



The chief assumption which we have to make, then, is 

 that some free-swimming ciliated Ccelenterate of tiie very 

 simplest type, instead of becoming early attached, continued 

 to be free-swimming long enough to put out buds. There is 

 nothing improbable in this. Drifted away by currents, 

 thousands must have missed finding anything to attach them- 

 selves to. In times before the seas swarmed with carnivorous 

 fish or Crustacea — both, 1 believe, descendants of the Worms 

 whose origin we are discussing — there would be abundance of 

 opportunity for some of these unattached forms to lead a 

 free-swimming life with safety, feeding on still simpler forms, 

 animal and vegetable. 



* This method of deducing the Scyphozoa with ectodermal gullet from 

 the Hydrozoa without ectodermal gullet is to my mind preferable to the 

 belief, entertained by Sedgwick and others, that the mesenteries were 

 developed primarily as folds for the increase of the digestive surface. 

 The differentiation of the muscles round the primitive mouth into 

 radiating bundles could hardlj* fail to result in the formation of internally 

 projectirg folds, the body being but a flexible sac frequently distended by 

 iiuid. The more strongly these ridges developed the more permanent 

 would be the tucking of the primitive oral aperture into the body, the 

 ectoderm around it becoming the lining of an oesophageal tube. The 

 advantages to the organism not only of this more perfect mouth, with its 

 stronger sphincter and radial muscles, but also of the increase in the 

 digestive surface afforded by the mesenterial folds, would lead to its 

 further development. 



