CONCLUSION. 315 



true periodicity of intensification and relaxation, which hitherto 

 has seemed to be irregular, simply because of the individual 

 character of the organism upon which they operate. 



Every day reveals to us new channels in the courses of nature ; 

 but as we trace them back to their source, we find them all to be 

 the branches of one great current, which forces everything before 

 it onward and straightforward into the universal ocean, the end 

 of all things and the beginning of the new; that great reservoir 

 from which the elements of all beings are derived, and to which 

 they all return, in one eternal circle of changes, from the elab- 

 orate composition of the body of the growing man to his going 

 down again into the disintegrating, fluttering atoms, and their 

 final diffusion into the primitive vapors. 



ADDENDUM. 



ON page 162, line 20, at " vibrating lash," add as a note the following: 

 I have ascertained by observation, while these pages were going through the 

 press, that this so-called lash is an optical illusion^ and that it is really a row of 

 closely set, vibrating cilia seen edgewise, or foreshortened ; just as the teeth of 

 a comb would appear if their points projected toward the eye. This has been 

 confirmed by investigations of other species of Vorticellidae, e. g. Epistt/lis galea, 

 Ehr?, E. grandis, Ehr ?, Vorticel/a nebulifera, Ehr., Carchesinm poli/pinum, 

 Ehr., and Tricliodina pediculus, Ehr. ; and I conclude, therefore, that the so- 

 called " bristle of Lackman," described and figured as long ago as 1856, (Lachman 

 in " Miill. Archiv. 1856,") does not exist in nature. See, for further details, 

 my forthcoming memoir on the " Anatomy and Physiology of Trichodina" in, 

 the "Memoirs of the Boston Society of Natural History." 

 CAMBRIDGE, Mass., November 16, 1865. 



