92 THE AMERICAN MONTHLY [Mar 



one to the other is easily understood when their life history- 

 is known. As these papers are intended to be a mere recit- 

 al of the facts observed I say little about theories. The cul- 

 ture filaments were about 1-4 inch in length and small in 

 proportion. 



The second morning after these gatherings were placed in 

 the open air and sunlight, the surface of the sediment in one 

 of the glass dishes was completely covered by a display of 

 hydroids, the sea anemone in minature circles, of pure 

 white pearly tentacles from 1-2 inch in diameter down to 

 those barely visible. A slight jar would cause them all in- 

 stantly to retract and disappear. The tubularian worms 

 also began to show their presence. Most of them were of 

 single proboscis kind but I found some with eight tentacles. 

 Six of them were somewhat club-shaped and two consider- 

 ably longer and tapering, resembling closely the arms of a 

 squid. Among the Pleurosigma fasciola, was found the 

 pointed cylindrical form previously found at Leete's Island. 

 This was a little longer than P. fasciola, tapering at both 

 ends with a slight knob at the point. It was ver}^ active, 

 traveling faster than the Pleurosigma, It was destitute of 

 silex. They could be bent up double, in form of an ox -bow, 

 without injury. Then when we removed the pressure they 

 straightened out and moved on as fast as before. My pre- 

 vious experience with Nitzchia closterium forced me to think 

 that these were immature Nitzschia taenia, chiefly because 

 quite a number of mature and normal forms were found 

 with them. The mature forms were more than three times 

 as long as the others and large in proportion. They were 

 rigidly siliceous and could not be bent without breaking. 



The weather becoming cold the cultures were moved into 

 an upper room to set before the south window where they 

 had the full sunlight. But the room was cool enough to 

 prevent too much rise of temperature. Here new colonies 

 developed quickly: Navicula, Amphora, Nitzschia, Melosira 

 and others. Some were enveloped in gelatinous mucus, but 



