88 JOURNAL OF THE [October, 



This accidental discovery of the motility of the protoplasmic 

 covering of the Afuphiprora induced me to see what was already 

 of record in relation to the cause of the directive motion of many 

 genera of the Diatomaceae, but more particularly the Naviculse. 

 I forthwith consulted all the available references to the life history 

 of the Diatomaceae within reach. Neither the " Encyclopaedia 

 Britannica," latest (ninth) edition, " The Columbian Cyclopaedia " 

 (1892), "Micrographic Dictionary" (1856), " Carpenter on the 

 Microscope" (1856), Rev. Francis Wolle's "Diatomaceae of 

 North America" (1890), " Generalities, on the Diatomaceae," of 

 Count Abbe Francesco Castracane (1884), nor the address of 

 ex-President Charles F. Cox before this Society, entitled " What 

 is a Diatom ?" and published in full in the Journal (January, 

 1892), contained the slightest reference to, or a suggestion of the 

 phenomena partially described in the preceding introduction, but 

 most or all of the authorities confined their notice to the distinct 

 and evident motion of translation of the diatom trustule in a simple 

 direct or retrograde motion. The mystery of its motion was left 

 involved in hypotheses, and no satisfactory solution was offered 

 by the various observers. That any diatom had a dual or a sub- 

 sidiary motion was everywhere regarded in the negative or not 

 entertained at all. The Amphiprora, which clearly exhibits this 

 dual power, is not mentioned at all. The fact that Amphiprora 

 has some of the attributes of protozoan life, rather than that of 

 plant life, had been hitherto overlooked, or at least seems to not 

 have been specifically alluded to, especially as appears in Wolle's 

 "Diatomaceae of North America," which presumably should give 

 the highest reach of experimental research obtaining on this sub- 

 ject to the year 1890. In the opinions submitted therein the 

 cause of the motion of diatoms remains a mere hypothesis re- 

 quiring elucidation. And no authors so far have touched upon 

 the subject of the dual or compound motion exhibited by Amphi- 

 prora ornata or any other species of Amphiprora. 



After my initial experience related above, I made a second visit 

 to the bay shore, and carried along a collecting bottle, into which^ 

 from a new supply of the peculiar moss-like water plant, I ex- 

 pressed as much fluid from it as I deemed necessary, and at night 

 proceeded to study it de novo. By the most delicate manipulation 

 known to me I freed the material from sand, and by repeated 



