HARDWICKE'S SCIENCE-GOSSIP. 



63 



sphere, whilst the other anemones more deeply 

 settled in the water survived. I have found paint 

 and varnish most injurious to aquarium animals. 

 Therefore it behoves all aquarium possessors to 

 take special care of delicate specimens at such 

 times and seasons when paint and its attendant 

 evils are inevitable. If a shiny coating of scum 

 from paint or varnish be allowed to accumulate on 

 the surface of the water and hinder the free passage 

 of air, the effects are almost sure to be fatal. To 

 prevent this, when neither the aquarium 'or speci- 

 mens can be removed, I have found it best to keep 

 the aquarium closely covered, but to give an extra 

 dose of oxygen, in the shape of more constant 

 artificial aeration, as, e.g., by syringing or briskly 

 stirring with a stick, when a constant current is not 

 available ; also to place open pans of water in the 

 room to receive the paint poison instead of the 

 tank. Therefore in aquarium-construction it is 

 well to avoid paint wherever possible ; and hence 

 also the enormous advantage of a continuous circula- 

 tion of water, because impurities from without as 

 well as from within have not time to accumulate in 

 one place, but are dispersed before they work evil. 



The question of atmospheric contamination is an 

 important one, and has been discussed by the Natu- 

 ral History and Microscopical Society at Birming- 

 ham, with reference to the probable injurious effects 

 of their tainted atmosphere on the proposed aqua- 

 rium in their murky town. Individual experience 

 on this point would be valuable. Can any one 

 briag it to bear ? 



After grieving over the untimely end of my first 

 Double Daisy, one day in July I was delighted to 

 find another double baby, so tiny it was not easy to 

 see its two mouths, much more feed them. But 

 patience and frequent food conquered ; although 

 she once wandered without leave, lost herself, and 

 got nearly starved. She now keeps a promising 

 situation, and sometimes stands nearly an inch 

 high, expanding f in., each disk measuring f in. 

 respectively. Both specimens resembled each other 

 closely in colour and all else, bearing decided marks 

 of the same parentage. The column is united 

 throughout, showing merely a slight line or de- 

 pression where the bodies unite. Two perfect 

 disks expand on the top, with duplicate sets of 

 tentacles, and are set side by side, not " developing 

 out of the side," as with " W. H.'s" "Double 

 Plumose Anemone." The digestive organs appear 

 to be distinct, yet connected ; if one head is fed, 

 the other is nourished ; if one half is probed, the 

 other shrinks in concert. I have noticed this sym- 

 pathetic action in our English corals, Balanophyllia 

 regia and Caryophyllia Smithii, whose corallums 

 appear still more distinct, and yet are united. I 

 have four double specimens standing side by side, 

 looking like separate individuals, growing out of 

 the rock; two others are more closely united, but 



all shrink and expand simultaneously, showing 

 intimate connection. I believe these double corals 

 are rare, though P. H. Gosse has figured one com- 

 pound specimen of C. Smithii with four disks and 

 sets of tentacles. I should be glad to hear of other 

 instances. These examples of single animals, with 

 occasional compound variations, are extremely in- 

 teresting, as showing connection with other genera, 

 and the gradual diminution of species, as our know- 

 ledge advances. 



On taking up Science-Gossip, after some years' 

 cessation, two things strike me forcibly. 1st. The 

 many unconscious contributions to Darwinism. 

 2nd. The want of standard knowledge on aquarium 

 matters generally. 



Whilst Darwin's theory of natural selection is 

 daily gaining ground, the practice of aquarium- 

 keeping seems to have advanced very little, if at 

 all ; and certainly appears not to keep up with the 

 times.* Exploded theories and practices are again 

 and again recommended, canvassed, and carried out, 

 and with the usual disastrous results. 



One loses his Warty Newts through a heavy 

 shower of rain, causing the aquarium to overflow. 

 Another wants to know whether it is possible to 

 keep "Pope-fish" in confinement, and complains 

 that they persist in dying, although there is "plenty 

 of water, which is frequently changed." With the 

 best possible intentions, another recommends the 

 introduction of growing red and green sea-weed, 

 and the regular supply of salt-water and animals, 

 from fishing-boats that discharge weekly at Billings- 

 gate. Others want to know why fresh-water fish, 

 tadpoles, &c., become " covered with a downy white 

 substance, or fungus," and die a horrible death, 

 and what is the cause of this " horrid pest " in the 

 aquarium ? 



All these things imply a constant, or periodic 

 change of water, totally at variance with the teach- 

 ings of the best-regulated aquaria. 



If your correspondent " H. C. C. M." will tell 

 me whether he changes his water, and if his rock- 

 work reaches above the surface, I may be able to 

 help him rear his tadpoles healthily from the egg to 

 maturity, and to avoid the fungoid growth for the 

 future. Most probably this very change of water is 

 one of the primary causes of fatality. It is never 

 necessary to change the water in a well-regulated 

 aquarium. The first supply should be the last, un- 

 less accident and unforeseen causes arise. 



Stocking is, therefore, not so difficult a thing as 

 G. H. Webb implies. It is difficult to get, trans- 

 mit, and keep rare and delicate aquarium animals, 



* It should be understood that these remarks refer to the 

 private aquarium- keepers, who ventilate their difficulties in 

 Science-Gossip, without eliciting higher information in 

 response, and not to the enormous strides made in public 

 aquarium-keeping, as, e.g., at the Crystal Palace, and all 

 others built and managed on the same principle. 



