204 THE AMERICAN MONTHLY [July, 



doplasmic contents into a single sporangial mass, thus at- 

 testing a living transmigration of the motile spherules, 

 and their re-appearance again on the completion of the 

 mature sporangial frustule resulting from this conjuga- 

 tion ; through which means, and by persistent observa- 

 tion, he was enabled to establish the fact that Surirella 

 splendida, with its double nucleus, is the sporangial de- 

 scendant of Surirella elegans, through conjugation alone. 



From the above we may recognize the following phe- 

 nomena, that as a result of conjugation, there follows a 

 union of two pre-existent masses of living protoplasm, 

 endochrome and contained motile spherules, and the re- 

 jecting or shedding of the inert siliceous frustular cases 

 of the progenitors. These interesting facts suggest the 

 following query. Can a single organism, arising from 

 the fusing together of two distinct living units and pre- 

 senting in its internal structure two distinct nuclei, be 

 regarded as a unicellular or single-celled organism : 

 there having been in the transition between the two 

 states, no cessation, suspension or stoppage of vitality in 

 the change from the dual lives to the resultant frustule ? 



Prof, Smith in his published papers, gives with full 

 detail the phenomena occurring through the full period 

 of conjugation, from its reception, until the sporangial 

 frustule is fully formed, in which case we see that it 

 begins its active life with the motile spherules indicated 

 in their previous condition as filling the endoplasm of 

 the diatom. 



In reflecting over the nature of the movements made 

 by the motile spherules, I felt that they must be actuated 

 by a flagellum after the manlier of the spermatozooids 

 but not in the manner characteristic of the zoospores of 

 Vaucheria and other plant alg.T, and sometimes des- 

 ignated as coniocytes. They are top-shaped, flagellate 

 bodies, which are known to ricliochet or spin around in a 

 free state when ripe and freed from their parent cells, 



