468 ORGANOLOGY. 



Algce, which we have not yet discovered to possess morphologically 

 definite organs. 



According to the observations of the senator Dr. Binder, it is not 

 infrequent to find in Laminaria digitata and saccharina that a new cell- 

 formation is organised upon the edges between the under stalked part of 

 the plant and the upper flat extended surface, from which the formation of 

 an entirely new upper flat part of the plant is produced, whilst the old parts 

 are at the same time destroyed. In the excellent collection of Dr. Binder, 

 I saw a number of instances of this process in its different stages in the 

 L. digitata. 



The other case appears to exist in the Ceratophyllum, in which single 

 leaves are eoccasionally east off about two lines above their origin, and again 

 produce from the stump a perfect leaf. I have already made known 

 this fact in my contributions to our knowledge of Ceratophyllum (Lin- 

 nsea, 1837) 



The healing process is very general in the vegetable world, and the 

 substance which is produced for the purpose is similar to suberous tissue 

 (cork), which I have fully described in my paper upon Cacti. But this 

 subject belongs rather to the pathology of plants. 



D. The Process of Nutrition. 



189. The collective nutrition of the plant embraces various 

 different processes, by which foreign matters are received into the 

 organism, are entirely or partially appropriated, and through which 

 that portion of such matter which is not fitted for the nourish- 

 ment of the system, or which would impede the vital processes, 

 is thrown off. These processes are physical, so far as regards 

 absorption and excretion ; chemical, so far as the changes pro- 

 duced in the substances ; and morphological, so far as they are 

 concerned in the fixation of the appropriated matters in definite 

 organic forms. With plants which are not furnished with special 

 physiological organs, we cannot pursue the subject of nutrition 

 according to the function of individual co-operating organs. Each 

 cell is nourished according to its own special nature, and in dif- 

 ferent ways. In studying the nutrition of the plant, we must, in 

 the first instance, observe separately the physical, chemical, and 

 morphological processes ; secondly, the varieties of the first, accord- 

 ing to the different nature of the media surrounding the plant 

 or its parts ; thirdly, distinguish the following peculiarities of the 

 physical and chemical processes in the entire plant for instance, 

 an essential vitality may exist in the individual cells of a plant, 

 and certain processes may be carried on within them without 

 producing any effect upon the neighbouring cells, and upon the 

 entire plant, whilst processes carried forward in dead cells of the 

 plant may exercise an important influence upon the surrounding 

 living cells, and thus upon the entire plant ; lastly, the distri- 

 bution of the absorbed matters in the entire plant must be kept 

 in view. 



