l893-J NEW-YORK MICROSCOPICAL SOCIETY. 99 



tively slow motion of a iV^. viridis can interest and hold the at- 

 tention, this interesting form must in a higher degree give cause 

 for admiration. Conceive a beautiful, strongly lined, golden- 

 hued oval rushing through the water with a speed outdistancing 

 all other forms that I have ever seen in motion. When this is seen 

 it is almost impossible to disassociate the idea of a strongly pulsat- 

 ing life and animal energy from this little creature. To call it a 

 "simple lowly plant " would be to treat it with a presumptive in- 

 dignity. If one were permitted to speculate as to the character 

 of its motion, the mind might conceive of vibratile pulsations 

 as swift as the undulatory waves of light, or as the rapid alterna- 

 tions of the electric arc current in producing its light, if we take 

 into consideration the diatom's minute size and its energetic prog- 

 ress through the water by the imagined pulsations of its invisi- 

 ble protoplasmic sheath. 



Lastly, in relation to another character of motion — that of the 

 Bacillaria paradoxa. When we have seen that the ribbon of con- 

 jugate frustules is brought to a straight line with terminal frus- 

 tules, taking the order of "right dress, '^ and that suddenly the 

 end file leader darts off at a rapid stroke to the end of its neigh- 

 bor, and that the others do the same in quick succession, until 

 the whole line or group have passed each other, and then repeat 

 the same movements in a retrograde manner, we have viewed a 

 life movement of the most curious interest and truly paradoxical 

 in its nature. If we carefully analyze the consequences of these 

 successive phases of motion, we are forced to admit that each 

 frustule has a sheath of a colloid or gelatinous character (some- 

 what like the coleoderma of De Brebisson) that allows the con- 

 tiguous sides of each frustule to coalesce or anastomose and sep- 

 arate with equal facility. If this were not the case they could 

 not live in collective communities. These facts substantiate, 

 without staining or other experimental expedients, the truth that 

 this diatom, and possibly all diatoms, are invested with a proto- 

 plasmic mantle imbued with life, and capable of being paralyzed 

 or killed instantaneously by staining agents, and that this proto- 

 plasm has some of the characteristics of the protoplasni of the 

 protozoa. 



In the brackish material I witnessed a small Amphora, quiet and 

 motionless, upon the flat surface of which a bacterium seemed to 



