966 EEPOET OF COMMISSIONER OF FISH AND FISHEEIES. 



ing primary considerations. Any attempt at biological investigation 

 which disregards the special requirements and natural habits of the 

 lorms of life under investigation must result in disappointment. A cu- 

 rious instance in illustration of this point is quoted from The Familju 

 Aquarium, written by Butler : f 



" There are plants, too, which will not thrive in tranquil waters! 

 Sir John Paxton, knighted for his successful conception of the plan of 

 erecting the novel building so renowned and imitated as the Crystal 

 Palace, discovered this fact when he was a simple florist to the Duke of 

 Devonshire. A gigantic South American water-lily, brought from the 

 river Amazon, and well known at the present time as the Victoria regia^ 

 refused to flower under his care in the elegant tank he had prepared 

 for it. Suspecting at length that the want of motion in the water might 

 have something to do with its contumacy, he arranged a little paddle- 

 wheel in such a manner that a mimic stream should roll over it, and 

 thus in its fall into the tank continually agitate its contents. The ruse 

 was successful. The lily imagined itself once more at home, and being 

 perfectly at its ease expanded its giant flowers without further reluc- 

 tance or solicitation." 



The aquarium tank, while being indispensable for purposes of close 

 observation in special cases of interest, is by reason of its great artific- 

 ialty (that is, unnatural light, and injurious temperature in warm 

 weather througb exposure to the atmosphere on all sides), generally 

 unfit for the generative development of fish, reptiles, crustaceans, &c., 

 although they may be kept alive in such tanks for long periods. But 

 for the purpose of close observation, such animals when at the proper 

 stage of development, may be safely transferred to aquariums for short 

 periods. 



The necessity of imitating nature being kept in view, it is evident 

 that the work is to be begun in the open air or outside of ordinary 

 closed buildings, in order that there may be an abundance of light. 



First, then, a piece of ground is needed proportioned to the magni- 

 tude of the operations. The proposed aqua- vivaria are simply excava- 

 tions (trenches or basins) in the earth, of any desired size or shape. 

 The excavations are to be lined with Portland cement to the thickness 

 of a half inch or more, the cement being simply plastered against the 

 earth walls without other backing. By excavating to but half the 

 desired depth and banking up the removed earth around the outer edges 

 of the basin, the aqua- vivaria will be raised above the reach of sudden 

 and heavy rainfalls. They will be much strengthened by sodding the 

 outside, though this is not necessary where they are permanently in- 

 closed after the manner of hot-beds. It will be necessary that they be 

 so inclosed during the winter months, and in some way heated during 

 the prevalence of extremely cold weather. A small amount of heat will 

 prevent the freezing of water under glass ; and it may be done simply 

 and inexpensively, after the manner of greenhouse heating. 



