66 BATH MICROSCOPICAL SOCIETY. 



most exposed coasts, lashed by the fiercest waves in the rocky 

 pools left by the sea water. To know anything of their life and 

 beauty one must study them on the spot, if you wish to see them 

 alive, remembering that of all fluids sea water corrupts the soonest 

 and becomes unfit to sustain marine life. But every stream and 

 every pond will yield materials for abundance of study to him 

 who keeps his eyes open to these things. 



Here we have the Kennet and Avon Canal,"where most of the 

 species of Rotifera and Entomoslraca may be found in abund- 

 ance, as well as various kinds of water plants, Potomagetons, etc. 

 It needs some experience in the search, and some knowledge of 

 the localities, to discover these treasures, but it is well worth the 

 trouble. With such advantages before them the members of the 

 Bath Microscopical Society may well be expected to do something 

 in the way of investigation. 



Absorption of Organic Matter by Plants. — In a commu- 

 nication from Prof Calderon, of the Institute of Las Palmas, 

 Canary Islands, he contests the ordinary view that the nitrogen of 

 the tissues of plants is derived entirely from the nitrates and 

 ammoniacal salts absorbed through the roots. He does not, how- 

 ever, adopt the old theory that the source is the free nitrogen of 

 the atmosphere, but rather the nitrogenous organic matter which 

 is always floating in the air. The nitrogen of plants he divides 

 into three classes : — Necrophagus. the absorption of dead organic 

 matter in various stages of decomposition ; plasnwphagus, the 

 assimilation of living organic matter without elimination or dis- 

 tinction of any kind, between useful and useless substances, such 

 as the nutrition of parasites ; and biophagus, the absorption of 

 living organisms, such as that known in the case of insectivorous 

 plants. A further illustration of the latter kind of nutrition is, 

 according to Prof Calderon, furnished by all plants provided with 

 viscid hairs or a glutinous excretion, the object of which is the 

 detention and destruction of small insects. To prove the import- 

 ance of the nitrogenous substances floating in the air to the life of 

 plants, he deprived air of all organic matter in the mode described 

 by Prof Tyndall, and subjected lichens to the access only of this 

 filtered air and distilled water, when he found all these physiologi- 

 cal functions to be suddenly suspended — Nature. 



