106 



motion iti the stem and branches of a cluster, is en- 

 tirely derived from the polypi. Indeed at first sight 

 one would imagine, that the polypi fixed to the 

 branches of a cluster, spring from them, in the same 

 manner as the leaves, the flowers and the fruit of a 

 vegetable spring from it. On the contrary the branch- 

 es composing the clusters of polypi^ spring from the 

 polypi, which are at their extremities, and these po- 

 lypi, which at first appear to be fruits^ may rather be 

 termed the roots of them. 



The nature of Corallines, and the mechanism of 

 their polypi, (says Dr. Beysonnel) made me conjec- 

 ture, that it was the same with respect to sponges ; 

 that animals nested in the intestines of their fibres, and 

 gave them their origin and growth, but I had riot yet 

 seen the insects. Sponges appeared to me only as 

 skeletons, and I at length discovered the worms which 

 form them. They are of four species. 1. The tube^ 

 like sponge, 2, The cord-like sponge. 3. The fin- 

 gered sponge. 4. The honey-comb sponge. 



These four kinds only differ in form ; they have 

 the same qualities, and are made by the same kinds 

 of worm, they are all composed of hard, firm, dirty 

 fibres, sometimes brittle, separated one from another, 

 having large hollow tubes dispersed through their 

 subs'tance, these tubes are smooth within. These fibres 

 ivhieh consist of the twisted doubles, of tha sponge, 

 form as it were a labyrinth filled with worms, winch 

 are easily crushed, but 'having carefully torn the 

 sponges, and their gross fibres, I discovered the living 

 worms. 



These species of sponge commonly grow Upon sandy 

 bottoms. At their origin's we perceive a module of 

 sand, or other matter, almost petrified, round which 

 the worms begin to work, and round which they re- 

 tire, as to their last refuge, where I had the pleasure 

 of seeing them play, exercise themselves, and retire^ 

 by examining them with the microscope. 



The worms ate about one third of a line thick ? and 



