186 



Mid summer months, has caused the drying up of many ponds all over tho 

 middle and southern parts of England, and as far as my own experience goes, I 

 never knew such a number of bottoms of pools exposed to the sun and air, and 

 courses of brooks reduced to narrow threads of water ; in fact, several pools that 

 I never before observed to be bereft of water, have this year yielded to the 

 continued drought, while grasses and ordinary weeds have, in numerous instances, 

 occupied the place of dry and withered water-plants. 



The drying up of numerous pools, in such a continuously hot season as the 

 present one has been, must be obviously destructive to a great amount of animal 

 and vegetable life, more especially in the minute forms of both. The Pond- 

 weeds ( Potamogeton), Duckweeds (Lemna), the Hornworts (CeratophyUumJ, 

 Water-milfoils (Myriophyllum), as well as Zannichellia, Callitriche, Hydro- 

 tltaris, the Characecc, and other aquatic plants, must of necessity perish ; and 

 hero the Darwinian maxim of " the survival of the fittest" will not apply, as the 

 meteorological conditions produce the destruction of all alike. The suppression 

 of vitality in the Zy/jnccnuz, Confervaccce, Chetaphorcw, Vauclwia:, Oscillatorice, 

 and the minuter forms of vegetable life must be incalculable ; while Newts and 

 other aquatic reptiles, various small fishes, as well as the larva; of Water- 

 beetles, Dragon-flies, and other insects that inhabit ponds, must of necessity 

 perish. So, in like manner, the genera Lymnaa, Planorlis, Ancylus, and other 

 Water-snails, besides thousands of Infusoria, nourished at all times in stag- 

 nant waters, must be involved in the general destruction. 



When the naturalist only thinks for a moment of the numerous minute 

 organisms thus enumerated that inhabit stagnant waters, it must be evident that 

 countless multitudes of the minute and obscure forms of both animal and vege- 

 table life that inhabit 



" The green surface of the stagnant pool," 

 and the water beneath this green film, must have entirely perished, and been al- 

 together swept away from the scene of existence. Those who have studied the 

 infusorial world microscopically, or the cryptogamic botanist who has been in 

 the habit of taking water from stagnant pools to examine the almost infinite 

 forms of the Confervoidecc, the Desmidiaccce, and the Diatomacece, as well as the 

 unicellular Algce, will be better able than the casual observer to form an idea of 

 the countless forms of beings that are reduced to lifeless atoms by the drying up 

 of the ditches and pools of water. Having of late years often amused 

 myself with observing the varied forms of minute vegetation that abound in 

 pools and stagnant water, I will exhibit a few to you that those unfamiliar with 

 the subject may form an idea what a world of Wonders is in such places 

 hidden from the unscrutinising eye, yet ready for the revelation of the micro- 

 scope ; and it is here, on the mystic boundaries of animal and vegetable life, that 

 it is sometimes impossible to determine to which an observed form may belong, 

 for one organism simulates another, and animal and vegetative life in some 

 cases seems to be alternatively displayed by the same existence. But on that 

 disputable topic I 'hall not enter, only remarking that the extinguishment of 



