1869.] MISCELLANEOUS. 373 



have it in marked results from the application of the spectro- 

 scope. I have been enabled to prove the absolute identity of 

 chlorophyl or the green endochrome of plants with diatom hi or 

 the olive yellow endochrome of the Diatomaceae. The spectrum- 

 microscope is now too well known to need any description here. 

 The one I have used was made by Browning of London. It is 

 not at all difficult to obtain a characteristic spectrum from a liv- 

 ing diatom, and to compare it directly with that of a desmitl, or 

 other plants. 



I need not here give the results in detail. Suffice it that 

 from about fifty comparisons of spectra, I can unhesitatingly 

 assert that the spectrum of chlorophyl is identical with that of 

 diatomin." — SilUman's Journal. 



MISCELLANEOUS. 



How TO Furnish a Freshwater Aquarium. — It is use- 

 less, even were it possible, to give the exact amount of plants 

 that are necessary to keep an aquarium in order. A very few 

 pieces will be sufficient to purify the water, but as some water 

 plants are very beautiful, it may be desirable to have the maxi- 

 Dium rather than the minimum amount of them in the aquarium. 

 The fishes should have space enough to move around freely, and 

 at the same time to be seen to advantage. Bearing this in mind 

 my own taste would be to have as many plants as the tank would 

 allow. As the water in the tank is changed from time to time 

 the plants can be thinned out and the decaying stalks cut off. 



The live stock of the aquarium is generally selected from fishes, 

 lizards, snails, and mussels. One word as to the propriety of ha- 

 ving many kinds of fish together in one tank. Some fish, such as 

 sticklebacks or pickerel, are so voracious that either the other 

 fish are wholly eaten up by them, or else their fins or tails are so 

 maimed that they become objects of pity instead of amusement. — 

 Again, in selecting a stock of fish we should try to have them of 

 a size proportioned to the tank they are to be put in. It is a 

 great mistake to have in the tank a fish so large that it can hard- 

 ly turn about ; aa a general rule, in our common sized tanks, the 



