216 The American Naturalid. [Marcb, 



8th. Nyctitropic movement of leaves. 



9th. Mechanics of irritation movements. 



10th. Flying apparatus of fruits and seeds. 



All of these ten subjects he treats from his own standpoint, 

 giving the results of his own experiments and study, except, 

 perhaps, the last one, which is sometimes omitted for lack of 

 time, and it is one to which he has given less attention than 

 to the remaining nine. 



From these ten subjects there may be selected three in 

 which his opinions are diametrically opposed to those of Sach8 

 and his followers ; several of the rest are not treated at all 

 in the latter school ; and to the three here mentioned may be 

 added two more important questions in which Schwendener 

 differs radically from other physiologists. He gives the fol- 

 lowing list as including the most important questions of differ- 

 ence between his opinions and those of Sachs. 



1. The problem of the ascent of water. 



2. Cause of the year's ring. 



3. Bending aside of the medullary rays by the rind 

 pressure. 



4. Mechanism of twining stems. 



5. Turgor, its influence on growth of cell wall. 



These may be said to represent fairly the important points 

 which serve to separate the new school from the old. It is 

 hoped a brief consideration of some portions will be sufficient 

 to vindicate the right of the new school to this title, claimed 

 for it here for the first time. 



The problem of the water ascent is one in -which Schwend- 

 ener not only differs from Sachs but also from a large number 

 of other botanists, who cannot be considered the followers of 

 Sachs. The theory held by the latter and his school is, that 

 the water rising in stems more than 30 feet high is for the 

 most part carried through the lignified cell-walls. Schwend- 

 ener and a large number of other botanists believe it is carried 

 through the lumina of the cells. The difference, however, in 

 the theory as taught by Schwendener and these other botamsts, 

 some of whom are, in other respects, hi- followers and adher- 

 ents, is that they claim to give an exact explanation of the 



