110 Mr King'^s apparaUisfor impregnatmg liquids mth gases. 



ment takes place to facilitate the exit of the embryo from the 

 inert body of the parent. The above remark of Dr Rosen- 

 thal respecting the Medusa, shows that it takes place in the 

 class of Radiated animals ; and I have shown in a former num- 

 ber of this Journal (No. xiii. p. 121.), that in the class of 

 Molluscous animals, the escape of the foetus from highly com- 

 plicated ovaria, as those of the Buccinum, is effected in like 

 manner by the rapid vibration of ciliae placed on the surface 

 of the young. The transformation of the ova above described, 

 from their moving, irritable, and free condition of animalcules, 

 to that of fixed and almost inert zoophytes, exhibits a new 

 metamorphosis in the animal kingdom, not less remarkable 

 than that of many reptiles from their first aquatic condition, 

 or that of insects from their larva state. Ulvae and confervae 

 have been seen to resolve themselvesinto animalcules, (Schweig- 

 ger^s Beobacht. auf N. R, s. 90. J, and Professor Aghard has 

 seen these animalcules reunite to construct the plants. Mosses 

 and Equiseta are found to originate from confervas, (Mem. du 

 Mus. tom. ix. p. 283.^, and all the land confervse with radi- 

 cles appear to pass into the state of more perfect plants. The 

 Oscillatoriae which cover the stones in our fresh water pools 

 with a green and velvety crust, resolve themselves into ani- 

 malcules and lively moving filaments, whose motions have 

 been described by Saussure, Vaucher, and others. The glo- 

 bules of our blood have been seen to arrange themselves in- 

 to fibres, (Phil. Trans. 1818. p. 112.), and the densest fibres 

 have been resolved into their regular component globules. 

 But few known changes in the vegetable or animal kingdom 

 are more singular than that which the ova of zoophytes present 

 in passing from the state of lively, free, and spontaneously 

 moving bodies, to that of fixed horny roots, or equally inert 

 calcareous cells. 



Art. XVIII. — Description of an Apparatus for ImpregnfiU 

 ing Liquids with Gases. By James King, Esq. Commu- 

 nicated by the Author. 



In the year 1820 I had the pleasure of suggesting to Dr Hope 

 the construction of an apparatus for impregnating liquids with 



