1908] CURRENT LITERATURE 469 
liquids. But since neither b nor c, as the author himself points out, can exercise 
any effect on turgor pressure, it is difficult to see why they should be reckoned 
as components. The study of the osmotic pressure of the solutes in cell sap and 
wall is carried out with a show of mathematical formulae that look formidable, 
but the data are really not yet adequate for exactness. The experimental results 
show that the observed osmotic pressure is always less than the calculated, which 
is due to the greater or less but general permeability of the protoplasts, a feature 
too much overlooked hitherto, though clearly pointed out by various investigators 
and a priori obvious. The effects of temperature changes, especially between 
0° and 20° C., were also examined. A warning against conclusions based on 
the exclusive use of KNO, as a plasmolytic agent without correction for permea- 
bility is given. 
In a later paper,s LepEscHKIN reports the results of a study of the per- 
meability of the pulvinus cells of Phaseolus and Mimosa, in which this proves 
to be surprisingly high. The solutes (except sugar) escape so rapidly when the 
tissues are brought into water, and especially into running water, as to reduce 
the apparent osmotic pressure (determined by the isotonic coefficient method) 
by 25 to 50 per cent. A change in the permeability of the plasma membranes 
may alter the turgor pressure by several atmospheres. LEPESCHKIN proposes 
to show in another article that such changes really occur (as has been hitherto 
assumed) under the action of various agents.—C. R. B. 
The blood of plants.—PALLADIN’s preliminary paper+ bears a rather striking 
title, which will be just enough if the theory proposed is fully established. Cer- 
tain colorless chromogens, probably products of protein decomposition, have 
been found in plants, and these become pigments (already familiar to common 
observation in various discolorations produced on cutting or crushing) under the 
action of oxygen in the presence of oxidases. These respiratory enzymes are 
therefore to be considered as pigment producers, and the respiratory pigments 
doubtless include a number of pigments already known, such as those of the 
indigo plants. PaxLapIN proposes to call all of them, irrespective of their chemi- 
cal composition, phytohematins, in recognition of the identity of their physiologicay 
significance with that of the hematin of the blood. To show this it was neces 
to find reductases in plant as in animal tissues, and PALLADIN announces 
- discovery. These enzymes reduce the respiratory pigments, which then 
n down to CO,, and H,0, etc. The following scheme shows the relation 
the various respiratory processes: 
3 Peis W. W., Ueber die osmotischen Eigenschaften und den Turgor- 
« der Blattgelenkzellen der Leguminosen. Ber. Deutsch, Bot. Gesells. 26a:231~ 
1go8, 
4 PaLiapin, W., Das Blut der Pflanzen. Ber. - Deatack Bot. Gesells. 26a:125~ 
1908. : 
