444 BOTANICAL GAZETTE [JUNE 
character of a pure NaCl solution, points out that the salts or electrolyte 
in general do not exist exclusively as such in living tissues but are ionized, 
and these ions are united with the proteids. “The great importance of these 
ion-proteid compounds lies in the fact that by the substitution of one ion 
for another the physical properties of the proteid compounds change. This 
accords with Dr. Loeb’s own results on variable absorption of water by 
muscle, according as Na, K, or Ca ions were present, and explains some facts 
regarding the effects of salts upon turgor in plants. Loeb found pure NaCl 
solutions of equimolecular strength with sea water poisonous to Fundulus, a 
fish which can endure a great increase in the concentration of sea water, 
non-contractile in NaCl, and was able to control its contractility at will by 
varying the solutions; ciliary movement and development in young larvae 
of the sea urchin could be modified in the same way. Loeb’s conception 
as to the relation of metal ions to proteids and the protoplasmic functions 
Suggests reexamination of the conclusions as to the elements necessary 
to the healthy development of plants. These conclusions have been based 
chiefly on the use of nutritive solutions from which certain salts were succes- 
sively omitted. One element, however, may only be necessary to antagonize 
the action of another.—C. R. B 
THE FOURTH PAPER in Professor F. O. Bower's series entitled ‘ Studies 
only considers the homosporous forms. As thus limited, he proposes the 
three following great divisions of homosporous Filicales, which he calls sub- 
orders: Simplices, Gradatae, and Mixtae. 
; It may serve to a better understanding of the characters upon which these 
divisions are established to indicate the groups which they include. The 
Cyatheace, Dicksonieze (exclusive of Patania Woodsia, Hypoderris, and 
Deparia), and Dennstaedtiinae; the Mirtae include Davalliez (exclusive of 
> Phil. Trans. Roy. Soc. B. 192 : 29-138. pls. 2-7. 1899. London: Dulau & Co., 
37 Soho Square, W. 83s. 
