1883.] 



MICROSCOPICAL JOURNAL. 



203 



has been accomplished in solving 

 problems that have long puzzled 

 naturalists. A very choice morsel for 

 the palate is the white-bait, a small, 

 delicate fish, about an inch in length, 

 which is sold at an extravagant price 

 in the English markets. It was long 

 an undecided question among natural- 

 ists what these little fishes became 

 when they attained their growth. It 

 was supposed they grew into the her- 

 ring, Cliipea /la/Tiigiis, but owing to 

 their peculiar habits no one could 

 prove the relationship. Prof. Saville 

 Kent, however, succeeded in keeping 

 them alive for eighteen months in the 

 Manchester aquarium, and was thus 

 enabled to prove that the white-bait, 

 Cliipca alba, did develop into Clupea 

 harcngus. Such an observation could 

 not have been made except under the 

 exceptionally favorable opportunities 

 afforded by large tanks supplied with 

 thoroughly aerated, constantly run- 

 ning water, which can only be found 

 in aquaria established for purposes of 

 exhijiLion. 



At the celebrated Brighton aquarium 

 which is one of the most successful 

 in England, for it has paid well, an- 

 other disputed question has been 

 settled in an interesting manner. It 

 was supposed by some naturalists and 

 fishermen that the ova of the cod and 

 the whiting were deposited on the sea- 

 bottom, and if so it was feared that 

 trawling would destroy the spawn, 

 and thereby diminish the product of 

 the fisheries. Experiment proved, 

 however, that the eggs of both those 

 fishes would not sink, but floated on 

 the sirface of the water. At the same 

 aquarium the rapidity of the growth of 

 salmon has been studied. Not to 

 weary the reader with other facts of 

 this kind, probably enough has been 

 said to indicate the utility of large 

 aquaria for purposes of scientific in- 

 vestigation. 



A few words now concerning the 

 principles which determine success in 

 maintaining the necessary conditions 

 for life in aquarium tanks. It is need- 

 less to review the gradual progress of 



nd litoon plant 

 er oA a large 

 I Mr.iBarnum 

 whaled, some 



knowledge concerning acjuaria. It is 

 well known at the present day that 

 if the proper balance of animal and 

 plant life be maintained in an aqua- 

 rium, the products of respiration of the 

 animal are removed from the water by 

 the growing plai\ts, and oxygen is 

 given out in reluro. Although this 

 perfect balance caii be reridilv main- 

 tained in small tanks at Homo, it is 

 not practicable to depe 

 life to aerate the 

 scale. In the year \\ 

 procured two living 

 sharks, and one or twolother inhabit- 

 ants of the deep, whiai he kept for 

 some time in tanks sup|lied with salt 

 water from the river. Yl'his was the 

 iirst public marine Iciuarium in 

 America, and the methocinow in most 

 favor for keeping an i mils alive in 

 tanks is the same as Mr. larnum then 

 adopted, except that insteld of pump- 

 ing the water directly froni its source, 

 a supply is stored in ulderground 

 cisterns, from which it is c(»tiauously 

 pumped into the tanks andlllowed to 

 flow back into the cisterna As the 

 water flows from place to pllce, it be- 

 comes well aerated; and fte same 

 water may be used for years! In the 

 Crystal Palace aquarium the eliibition 

 tanks have a capacity of 20,oocfrallons, 

 while the reservoir contains 100,000 

 gallons more. It is a question Whether 

 such a large reserve supply is] 

 sary, or indeed, whether any c( 

 able volume of water besides \|jiat 

 in the tanks need be kept. The 

 two benefits to be derived fr( 

 however, first, the temperature If 

 large volume in the cistern muS 

 main tolerably constant througl 

 the year, and second, any disturbace 

 in one of the tanks, causing the w^er 

 to become foul or turbid, can be 

 mediately remedied by drawing tlfie 

 water off into the large cistern, when 

 it mingles with such a comparatively 

 large volume that it can do no harm. 

 The loss of water at the Crystal Pal- 

 ace aquarium has been calculated as 

 only about 2 per cent, by leakage. 

 Although this article has especially 



