100 JOURNAL OF THE [October, 



be struggling to cross its body, being apparently held by the 

 resistance offered by the protoplasmic layer of the Amphora. It 

 is well known by those who have made a study of the simple 

 Bacillus leptoihrix buccalis of the teeth, that if these are taken 

 directly from the teeth and put in a small drop of violet ink, and 

 a cover glass placed over them, their power to travel will be evi- 

 dent. They move along in a kind of scintillating way, and 

 change their position moderately fast while being observed, so 

 that there is no need of mistaking a bacterial movement for what 

 is known as the Brownian movement of powdered or finely 

 divided inert or mineral particles. The bacterial movement has 

 a distinct and peculiar character. The bacterial form alluded 

 to as traversing the surface of the little Ajnphora was evidently 

 under the restraining influence of a power lodged in the external 

 covering of the Amphora. I did not, however, follow it until it 

 freed itself from the Amphora. I may remark that this closes an 

 interesting variety of experimental and ocular evidence bearing 

 on the character of motion in the diatom, and also of its proto- 

 plasmic surface. 



Resuming the thread of my study of the diatoms in the bottle 

 of material from Whistler, Ala., late in the evening of the fifth 

 day of my experimental studies, giving the final examination to 

 the condition of the diatoms at the spot admitting daylight, I 

 was surprised to find that during the interval since I had last 

 ■examined it exactly fifty desmids had come up and fixed them- 

 selves in the illuminated area of one-quarter inch diameter. 

 These were all of one species — Micrasterias rotata. The diatoms 

 still had life. But on the next morning — the sixth day — I found 

 that all of the desmids had dropped back into the sediment and 

 were no longer visible, and that the diatoms were all dead and 

 glued to the sides of the bottle by what I took to be colonies of 

 bacteria or some fungoid matter. A new class of life had 

 usurped the territory in continuing the struggle for existence. 

 Collaterally with the living Whistler diatoms, I studied occasion- 

 ally the bottle containing the Mobile Bay brackish-water diatoms, 

 and I incidentally observed that the rhizopod, Arcella vulgaris^ 

 was quite common on the sides of the bottle. From the same 

 source I studied the movement of the living pseudopodia of Dif- 

 Jlugiapyriformis. I was previously familiar with Amoeba proteus, 



