1808.] NATURAL SCIENCES OP PHILADELPHIA. 117 



Prepared in this manner, the isolated cells and short segments of 

 filaments present the appearance indicated by figures 3 to 5, PI. VI. 

 The gradual development of the foot-like organs from an intercellu- 

 lar plasm is shown in figure 3 ; and in figure 6 is shown the deteri- 

 oration of these organs, which takes the form of an overproduction 

 and liquefaction of gelatinous substance, and ends by gradually 

 bringing to rest all the moving cells of a gathering, and entangling 

 them in masses and threads of jelly. During this degeneration 

 many of the cells die, but some survive with every appearance of 

 health, though necessarily devoid of motion. 



In figures 8 and 9 is shown the appearance, under 1,000 diame- 

 ters, of the stained processes from the valve view and from the ven- 

 tral girdle view. The outer and larger process, mainly gelatinous, 

 shows a general mass slightly tinted only, outlined by more heavily 

 stained grains within the substance. These grains take the eosin 

 as do the protoplasmic granules of the inner cell. The smaller pro- 

 cess, which seems to be somewhat shrunken by the staining with 

 eosin (compare figures 4, 5 and 6, PI. VII) are of a deep and nearly 

 uniform red, and are in close apparent contact with aggregations of 

 protoplasm within the frustule. 



The small and apparently constant bead-like bodies around the 

 circumference of the curving gelatinous masses have no perceptible 

 thread-like connection with the more richly protoplasmic processes 

 at the corners, and their significance is somewhat doubtful. They 

 probably have some relation to a current of protoplasm which would 

 seem to issue from the cell and return to it. 



Structure oj the frustule. — The existence of a " pseudo-nodule " 

 on the ventral side of the valve, near the end, has long been known ; 

 but that there is a raphe at the end of the frustule has not, I be- 

 lieve, been stated. The photographs in Plate VII, which I owe to the 

 kindness of Mr. F. J. Keeley, show clearly both the existence of 

 this raphe and the presence, especially on the ventral girdle, of 

 several channels in the silica which seem adapted to lead currents 

 to and from this raphe and the pseudo nodule. 



The exact shape of the raphe itself, and its extent, remain to be 

 determined ; and indeed the problem presents difficulties, for the 

 position of the raphe on the end of the frustule would necessitate 

 sections for its study. 



When a very dilute aqueous solution of gentian violet is dropped 

 upon living and moving Eunotia major, and afterward washed off, 



