DEVELOPMENT OF EOLIDS. 245 



there Polypes, Polyzoa, and ova. For these we want the 

 microscope, one of those " intellectual tubes which give thee 

 a glance of tilings that visive organs reach not ; " * and many 

 a blissful hour may we spend over its revelations. We may 

 hear, indeed, that our perplexed vassal reports us as spend- 

 ing the day " a-squinting through a glass ; " but her sarcasm 

 is harmless, and the revelations are thrilling. Wliat can be 

 more interesting than to watch the beginnings of Life, to trace 

 the gradual evolution of an animal from a mass of cells, each 

 stage in the evolution presenting not only its own character- 

 istics, but those marks of affinity with other animals which 

 make the whole world kin ? To watch the formation of 

 blood-vessels, to see the heart first begin its tremulous pulsa- 

 tions, to note how Life is, from the first, one incessant struggle 

 and progress — these keep us with fascinated pertinacity at our 

 study. 



Among other things, I have watched the development of 

 the Eolis and Doris with great interest ; not the less so from 

 the fact that, in spite of the marked differences between the 

 developed animals, their course of development is so indistin- 

 guishably similar. On the rocks, or on the side of your 

 vases, you may see a long coil of spawn, looking like delicate 

 pearl beads enveloped in a perfectly transparent membrane. 

 The first thing which will surprise you, on commencing the 

 investigation, is that the division of the yolk-mass is imlike 

 that of most other eggs. In the first place, it is not sym- 

 metrical ; in the next place, it is not always the same. Some- 



* Sib Thomas Bkowne. 



