1904 BOTANICAL GAZETTE [SEPTEMBER 
must be about 1 per cent. This illustrates how sensitive the sweet 
pea seedling is to traces of ethylene. Moreover, it seems fairly 
well demonstrated that for plants in general (but by no means all) 
ethylene is relatively very toxic. 
The remarkable capacity of ethylene to induce swelling naturally 
suggests the question, What is the effect of ethylene on plant 
metabolism? A certain amount of work has been published on the 
effects of illuminating gas and “laboratory air,’’ which should 
furnish required data on the question, since in both those gaseous 
mixtures ethylene has probably been an important factor. Never- 
theless, with regard to the effect of ethylene as such, I have been 
able to find no literature. This was largely the reason for under- 
taking the investigation reported here, the work having as its sub- 
ject the determination of the changes brought about in plant tissue 
by ethylene. 
Historical 
Our knowledge of the changes in metabolism causing and accom- 
panying swelling of plant organs has been gained largely from 
investigation of the effects of anaesthetics, particularly ether and 
chloroform. For a general historical résumé of the literature of the 
effects of anaesthetics on plants, the reader is referred to an excellent 
paper by Hempet (11). The following consideration of the litera- 
ture deals only with the effects of anaesthetics on the chemical 
composition and the respiratory processes. 
JOHANNSEN (16, 17) found that certain concentrations of ether 
and chloroform caused an increase of soluble sugars and a decompo- 
sition of proteins in bulbs of Crocus and seeds of pea and barley. 
But he also noted that very weak ether gave reversed effects, that 
is to say, favored starch and protein synthesis. His explanation 
for the increase in sugars and amino bodies was simply that anaes- _ 
thetics interfered with the condensation, but not with the hydro- 
lyzing processes. ZALESKI (36), working with Lupinus, found that 
protein synthesis was favored by ether and hindered by caffein. 
Butkewirscu (3) and BARTEL (2) both reported an increase of 
tyrosin in Lupinus, as an effect of chloroform. PRIANISCHNIKOW 
(28) was able to demonstrate a considerable increase of asparagin in 
Lupinus when the seedlings were grown in an atmosphere containing 
