262 Miscelianeous. 



numerous fibrils and buds. In the funnel-tube the roots made a 

 perfect tissue of fibres. In the dry earth of the funnel the roots 

 were less extensively developed, yet exhibited some juicy buds. 

 The stem and the young axillary leaf-buds were also full of sap. 

 The vcater-roots being cut away, the plant was put into garden soil, 

 and placed in a conservatory, where it grew vigorously, and in May 

 bore two offshoots. 



The experiment makes it quite certain that plants extend a por- 

 tion of their roots into the subsoil chiefly for the purpose of gather- 

 ing supplies of water. — Hennebei-g's Journal fur Landwirthschaft, 

 1863, p. 280 et seq. 



On the Air of the Swimming-Bladder of Fishes. 

 By A. MoREAU. 

 The author in the present paper describes the conditions under 

 which the amount of oxygen in the swimming-bladder of fishes may 

 be augmented. In the Physostomous fishes the duct of the swim- 

 ming-bladder enables the fishes to expel the air from the bladder, or 

 to take in air from the atmosphere by coming to the surface of the 

 water. 



The process to which the author subjects these fishes is as follows : — 

 The fish is placed in a vessel of water under the bell of the air-pump ; 

 as the air becomes rarefied, bubbles escape from the mouth and oper- 

 cular apertures. When, from the quantity of air expelled and the 

 descent of the barometer which measures the pressure within the 

 bell, it is supposed that nearly all the air is exhausted from the 

 swimming-bladder, atmospheric air is admitted into the bell ; and the 

 fish, which previously floated freely, immediately falls to the bottom 

 of the vessel, owing to the diminution in volume of the swimming- 

 bladder. The fish is then transferred (care being taken that he does 

 not get his head out of water) into a large vessel in which the water 

 is constantly renewed. The fish then lies at the bottom of this 

 vessel, creeping about rather than swimming ; his efi'orts to rise to 

 the surface are rendered abortive by a partition placed below it. In 

 a ievf days, or, with some species, in a few hours, the fish begins to 

 swim with more facility, indicating that the swimming-bladder has 

 become filled with fresh air, which has not been derived from the 

 atmosphere. The fish is then killed by the section of the spinal 

 cord effected under water ; the duct is tied and the swimming-bladder 

 removed to the mercurial trough, in order that the air which it con- 

 tains may be collected and examined. The analysis of this air shows 

 an amount of oxygen far superior to that of the air expelled under 

 the action of the air-pump, and also to that contained in the air dis- 

 solved in the water. 



Eight Tench were taken under the same conditions ; seven were 

 killed, and the air of their swimming-bladders gave 8 per cent, of 

 oxygen. The eighth was treated as above, and killed in a fortnight ; 

 the air of its swimming-bladder gave 60 per ceut. of oxygen. 



