274 Meyen's Report for 1839 on Physiological Botany. 



whole plant lives but several leaves die. This fact is certainly 

 quite true, but we must explain it otherwise. If only a small 

 quantity of a poison in a dissolved state is offered to a plant, 

 and this poison is not one of the very strongest, like hydro- 

 cyanic acid, it is carried up (like all other dissolved sub- 

 stances) with the water through the stem into the leaves, 

 where the process of digestion takes place ; here, therefore, 

 the poison collects and kills, but the whole plant does not die 

 from its effects, because the quantity was too small to poison 

 the large number of cells with their contained sap. 



The practical part of the work begins, properly speaking, 

 at page 80, and this section treats most circumstantially of all 

 the different substances which have been recommended for 

 manuring the soil, and, indeed, as fully as any agriculturist 

 can wish ; hundreds of analyses of the manures accompany 

 the doctrines which the author brings forward concerning 

 their application. This is clearly not the place to give a spe- 

 cial account of what service has been done in this purely prac- 

 tical part of the work ; we will only mention here observations 

 and theories with which the author makes us acquainted in 

 order to explain the action of this or that kind of manure, be- 

 cause this is in close connection with the study of the nutri- 

 tion of plants. 



It appears, from all observations, that food in the bodies of 

 animals is not enriched with, but rather exhausted of matters 

 fit for manuring, because the nourishing parts are extracted 

 and retained by the animals ; if however we see sometimes 

 that animal excrements produced from a certain quantity of 

 food, manure more powerfully than the food itself, it is only 

 to be explained either by the quantity of mineral substances 

 which are mixed with excrement, or we deceive ourselves in 

 as much as the dung acts powerfully at first but does not exert 

 this action for a long time, while the food manures at first 

 feebly but afterwards lastingly. The dung of animals will, 

 however, always be the worse, the poorer their food is, and in 

 proportion as it is better digested and extracted by the ani- 

 mal. In speaking of the animal manures, the author al- 

 ways draws attention to the development of carbonate of am- 

 monia, which is a substance so exceedingly nutritive for plants, 

 and states that in the treatment of the dung the principal 

 object to be held in view is to retain that ammonia, which may 

 be done by solution in water, or still better by combining it 

 with humic acid, which is contained in sufficient quantity in 

 mould. With regard to the celebrated manuring with bones 

 which has been tried with such great success in England, 

 the author says he has convinced himself that nothing but 



