VOL. X.] PHILOSOPHICAL TRANSACTIONS. 21^ 



Possibly the fish, while alive, may have an ability to raise up this valve, and let 

 out air upon occasion ; which yet I doubt of, because other animals have no 

 such faculty of opening any valves made to stop the reflux of fluids. But I 

 verily think, there is in the coat of this bladder a muscular power to contract 

 it when the fish lists : for in many fishes it is very thick and opaque, like the 

 coat of an artery, which has, as Dr. Willis observes, such a muscular power, as 

 for example in all the cod kind ; in some, v. g. the hake, it is inwardly covered 

 with a red cameous substance, which I take to be muscular flesh; in others 

 it is forked at the top, and to each horn has a muscle affixed. Now the mus- 

 cular force need not be great, being still assisted by the water as the fish de- 

 scends ; the pressure of the water being much greater at the bottom than at the 

 top, as appears by the ascending bubble. But whereas it is said, perhaps the 

 fish can by its sides or some other defence, keep ofF the pressure of the water, 

 and give the air leave to dilate itself: it may be objected, if it can do so, what 

 needs then any air bladder ? the cavity of the abdomen may serve the turn. 

 To which I answer, that this power of dilating the abdomen by the muscles, 

 may assist fishes to rise, whose natural place is toward the bottom ; and the air 

 compressed in the bladder dilating itself as the fish ascends, facilitates the action 

 of the muscles. But those fishes that descend by contracting the bladder, 

 letting the contracting muscle cease to act, will rise again of their own accord, 

 the air within dilating itself, as we see in glass bubbles by compression of the 

 air in them descending, which as soon as the force is removed ascend spon- 

 taneously. Besides the flat fishes I before-mentioned, all the cartilaginous 

 kind, as well flat as long, want swimming bladders : what course they use to 

 ascend and descend in the water, I know not. Many of the eel kind have 

 swimming bladders ; yet can they hardly raise themselves in the water, by 

 reason of the length and weight of their tails : I suppose the air-bladder, being 

 near their heads, helps them to lift up their head and forepart. 

 Middleton, June 22, 1675. 



How to make all Sorts of Plants, Trees, Fruits, &c., grow to an extraordinary 

 size ; from the Journal des Sgavans, N° 1 1 6, p. 356. 



The whole secret consists in sowing all sorts of grains and kernels, in beds 

 of earth, at the very time when the sun enters into the vernal equinox, and to 

 take them up when they are strong enough to be transplanted, at the time of 

 the full moon ; which time is always to be observed, if you would take them up 

 and plant them again. 



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