ARTIFICIAL CULTURES. 283 



.the nutrition theory mentioned is met with, however, in the fact that we are 

 now able to rear plants artificially — that we are in a position, with chemically 

 pure water to which we add some few chemically pure salts, to rear artificially 

 highly developed plants as well as the simplest Algae (and. mutatis mutandis, 

 also Fungi) — that from inconspicuous and often scarcely ponderable quantities of 

 vegetable substance, quantities of it as large as we choose may be produced in 

 this way. 



Such being the favourable position of affairs, I regard it as the simplest and 

 most instructive method to connect the main points of the theory of the nutrition 

 of plants, so far as they concern the food materials, wäth the description of an 

 experiment in artificial nutrition made with a highly organised plant. I think that 

 in this manner the essential and important points come into view more clearly than 

 with any other mode of exposition. In the year i860, I published the results of 

 experiments which demonstrated that land-plants are capable of absorbing their 

 nutritive matters out of watery solutions, without the aid of soil, and that it is 

 possible in this way not only to maintain plants alive and growing for a long 

 time, as had long been known, but also to bring about a vigorous increase of 

 their organic substance, and even the production of seeds capable of germination*. 

 Much disputed at first, this method of artificial plant-culture has been more and 

 more developed and perfected by various experimenters during the last twenty 

 years, so that it now affords one of the most important aids to the study of the 

 various questions of nutrition. The description of the ways and means by which 

 such an experiment is arranged and runs its course, in itself gives a clear illustration 

 of the most important processes of nutrition in a highly organised plant. 



We will assume that we have to do with the Garden Bean {Phaseolus) or the 

 Field Bean {Vicia Faba),oxM-a.\ze {Zea Mays), or Buckwhea-t {Polygonum /agopyrum), 

 plants with which the greatest number of experiments of this kind have hitherto 

 been conducted, although others, e.g. the Cabbage {Brassica) and Horse-chestnut, 

 &c., are also suitable for the purpose. 



It is best to allow the seeds of these plants to germinate in a box filled with 

 well-washed damp saw-dust, until the radicle is several centimetres long. After 

 the seedling has been carefully taken out and washed, it is fastened into a perforated 

 cork, Ä', as in Fig. 218, so that only the root dips into the water, N, of the vessel in 

 which the culture is being made. It is then only necessary to be careful that 

 the portion of the seed filled with reserve materials, ^ — the endosperm or the 

 thick cotyledons according to circumstances — remains sufficiently moist, without 

 however being submerged in the water. The apparatus, thus arranged, is placed 

 in a sunny window or in a suitable green-house ; care being taken however that 

 the root immersed in the water is sufficiently darkened. This is best accomplished 

 by placing the glass vessel in a hollow cylinder of cardboard. This precaution 

 is necessary, not so much because the roots might be injured by the light, as to 

 prevent green Algse from growing in the water and settling on the surfaces of the root. 



' Cf. 'Die iand7uir(Asi:haßt. Versuchsstationen,' Dresden, H. VI. i860, p. 219; and Bot. Zeitg. 

 i860, p. 113; and, further, Pfeffer's ' Pßamenphysiologie,' i88i, I. p. 253. 



