EE bere Mere eG L Be Tey aoe 
SG eat aw, - Lie ist Ne nl 7 tas) 
NOTES ON SCIENTIFIC RESEARCH. 143 
4 
44 
_ The beneficial influence of thé aldehydes is strictly limited to this class of bodies 
and is entirely missing with the ketones. Hence, the addition of any bodies interfering 
with the aldehydic character destroy the stimulating action. 
The effect of the activating action of the aldehydes is the same as results from 
taising the temperature, i.e., the aldehydes accelerate fermentation in the same manner 
as does gentle heating. If one considers that, according to the rule of van’t Hoff, a 
_faise in the temperature by 10° usually doubles the reaction velocity, one may easily 
_ judge the effect of the stimulating action of the aldehydes which without alteration of 
the temperature are able to accelerate the reaction by the 100-fold amount. 
j Since this activation passes off at low temperatures as well as at room temper- 
ature, it may be regarded as a means of the plant for rendering the necessary intensity 
of the respiration and hence the increase in energy independent of the surrounding 
_ temperature. Other phytophysiological processes may likewise be explained by the 
action of the aldehydes; for instance, any rise in the formation of aldehydes is possibly 
followed by an increase, and any rise in the consumption of aldehydes by a decrease, 
of the respiration — in short, the aldehydic metabolism influences the speed of phyto- 
_ physiological respiration. , | 
The following aldehydes were investigated: — 
Aliphatic aldehydes: — formaldehyde, propionic, n- and iso-valeric, d-valeric, 
d, l- i a eas m-Ccapronic, cenanthic, octylic, nonylic, and decylic 
aldehydes; 
Halogenated aldehydes: — chloral hydrate; 
Hydroxy aldehydes: — aldol, acetopropionic aldol; 
Unsaturated aldehydes: — citronellal, citral; 
Aromatic aldehydes: — benzaldehyde, cuminic, phenylacetic aldehydes; 
Aromatic hydroxyaldehydes and their Ue — salicylic, p-hydroxybenzoic, anisic 
aldehydes, piperonal, vanillin; 
Unsaturated aromatic aldehydes: — cinnamaldehyde; 
Cyclic aldehydes: — furfural, cyclocitral; - 
Dialdehydes: — glyoxal, iso- and terephthalic mdeeides 
Ketonic aldehydes: — methyl and phenyl glyoxal; 
Aldehydo acids: — aldehydosuccinic, o- and iso-phthalaldehydo acids, opianic acid. 
Generally, the aldehydes were dissolved in absolute alcohol and then diluted with 
water. The solutions were either clear or faintly turbid; on mixing with the yeast . 
extract and the sugar solution, always nearly quite clear mixtures resulted. 
How the aldehydes acted under various conditions appears from the author's 
abstracts of the experimental details. 
In experiments with fresh maceration juice from dry yeast of March 1915 and 
_ dextrose (tiso; 10 cc. juice; 2 cc. 5.p.c. dextrose solution), the following results were 
_ obtained : — 
tetng apt tate wns ene RD PPA CIA ae eae els anaes SEE AY MS 4 
COz development after 30 min. 60 min. 90 min. 120 min. 18 hrs. 
with Seetie apc alcohols. Si oO 0.4 7.2 9.0 17:5 - 
‘» 1 y m/100 propionic aldehyde .. 05 3.2 Teed 9.2 19.1 
TS ee »  tsobutylic es Memaetiauy-# | 7.9 ie 10.5 YAO 
ae Se »  twovaleric 3 bie Ace 7.0 OA aren OLE 18.6 
‘es ee »  #-Capronic ps IAS aR 7 4,7 7.4 9.2 17.8 
ag ts Fees »  cenanthic iy ce Tee es Be 8.0 BOL 10.7 106.1 
The marked action of the last-named aldehyde is of special interest. 
