154 JOURNAL OF THE [December, 



argentea, one of the Hydroidea. Though it was crisp and dry 

 and apparently dead, I indulged the hope that it might have a 

 spark of life, and so be revived. In truth, I had a pleasant 

 memory of the delight experienced by me many years ago vi^hile 

 watching with a hand-lens the little flower-like polypes which 

 buildup this graceful plant-like structure, catching their diminu- 

 tive prey. So I improvised an aquarium in a specie-jar. Re- 

 membering the turbid condition of the water when I put it into 

 the demijohn, I now poured it out with some misgiving. Barring 

 a little sediment which became disseminated in the water but 

 which soon settled, the water proved to be in excellent condition, 

 and in it my pretty Sertularia, anchored to a bit of shell, rose 

 like a fairy tree. Its very beauty increased my hope that it 

 would revive. Two days passed without any sign of life in the 

 hydroid, and then I became satisfied that it was dead. Still, as 

 something attractive, the jar with its pretty object was per- 

 mitted to keep its place in the window. 



Some of the streamlets near my home are impregnated with 

 iron oxide. A spring remarkable for its apparent purity yields 

 a sparkling water, which, if allowed to stand in a glass a few 

 hours, will deposit a yellow film of protoxide of iron. A few 

 days after establishing my miniature aquarium, I noticed a yellow- 

 ish-brown sediment at the bottom of the jar, and a similar but 

 thinner deposit on the sides. Query : Was this an oxide of 

 iron ? A drop of the substance at the bottom was put under 

 the microscope, and, to my astonishment, it proved to consist of 

 diatoms. A scraping was taken from the film on the sides of 

 the jar and examined, and this also was composed of diatoms. 

 Their immense numbers showed that they had been bred. in the 

 jar. But what and where was the originating stock? I assumed 

 that they were the product of diatoms parasitic on the Sertularia. 

 The inference was at least natural. Science has, however, but 

 little toleration for assumptions and inferences unless they are 

 well supported, so I set out to learn more about that oysterman's 

 " specimen." I sought the man, and, failing to find him, saw 

 his wife, from whom I got information in this wise : " That 

 oyster-moss ? Yes, I remember. You see, one day, as the 

 Cap'n was smoking his pipe, he happened to look up at it on the 

 wall, and, said he, ' Likely, Mr. Lockwood would admire that, 

 as he used to like anything out o' the water, and it is a good 



