294 BOTANICAL GAZETTE [ OCTOBER 
As an account of such an attempt the recent work of Cun- 
ningham deserves attention.’ 
As a basis for the theory upon which this author seeks an 
explanation of the mechanism of pulvini he devotes a large pro- 
portion of his work to the demonstration of the novel idea 
“that the great majority, if not all, of the transient spontane- 
ous movements of higher vegetable organisms, whether of a 
nyctitropic character or arising in connection with other condi- 
tions than the incidence or removal of sunlight, are not depend- 
ent upon the presence of any specially irritable and contractile 
protoplasts within the motor organs, but on purely physical 
processes connected either with fluctuations in the osmotic 
capacities of the tissue-elements, or with alterations in the rela- 
tions existing between local and general supply and loss of water.” 
{n support of this remarkable statement, but very little evidence 
obtained by an examination of the cell is advanced, but depend- 
ence is placed upon the external consistency and color of organs 
subjected to various reagents. Thus flowers of Hibiscus with the 
peduncle in water were exposed to ammonia gas in a moist 
chamber, and as they did not lose their form, while flowers 
similarly exposed to chloroform wilted, the conclusion was drawn 
that the osmotic activity of the dead cells was increased by the 
ammonia in the first instance. A final conclusion derived from 
similar experiments was that “ there is no direct relation between 
turgidity and the presence of living protoplasm in the bis 
elements,” but in some instances turgidity may be indirectly 
dependent on the protoplasm because of the necessity for 
the manufacture of osmotically active substances; 4 ce 
sion certainly at variance with almost all of the know? sti 
concerning the physiology of the cell. Not only does ' 
author deny the possibility of changes in the filtratave ie 
erties of protoplasm, but he disregards the simple POE 
Properties of this colloidal substance. He proposes # desig? 
*CUNNINGHAM, D. D.: The causes in the fluctuations in the motor organs 
n aviige Annals of the Bot. Gard., Calcutta 6: 1-145. 1895. 4t0. 7 
yith. coh 
