302 DECEMBER. 



inch in height, around the edges of our rocky pools, 1 or 

 a tiny thing which forms a little heap of transparent 

 globules, like pins' heads, attached to sea-weeds. 2 In 

 either of these, placed in a stage-trough of sea- water, 

 we can watch at leisure the performance of the various 

 vital functions in healthy action, with the knowledge 

 that the little subject has not been martyred to science, 

 but is all the while enjoying its humble life with per- 

 haps as much zest as if it were still environed by the 

 rough walls of its little native basin of rock 



In the tiny pin-head of clear jelly, the microscope 

 displays the branchial sac hanging free in the cavity, 

 like a bag of clear muslin. The oval cavities divided- off 

 by the rectangular ridges are about forty in number, 

 around each of which the ciliary waves incessantly roll, 

 as running spots of black. It is a very charming spec- 

 tacle to see so many oblong figures set symmetrically, 

 all furnished on their inner surface with what look like 

 the cogs or teeth of a mill-wheel, dark and distinct, 

 running round and round with an even, moderately 

 rapid, ceaseless course. These black, well-defined, 

 tooth-like specks are merely an optical effect ; they do 

 not represent any actual objects, but only the waves 



1 Clavelina lepadiformis. 



2 Perqphora Listen. For magnified figures of these animals the reader 

 is referred to my Tenby, Plate V., and Devonshire Coast, Plate xv. 



