SCIENTIFIC SUMMARY. 
77 
normal process of restoration of a deranged function in the plant ; how far 
this is the case with other plants must remain at present undetermined. 
Influence of Light upon Germination. — M. A. Pauchon has made a series 
of experiments to determine whether light has or has not any influence upon 
the germination of seeds. From various disturbing causes, his first experi- 
ments by the direct method gave no satisfactory results; he therefore 
adopted another plan, and compared the respiratory activity of seeds sub- 
mitted to different conditions of light and obscurity, measuring by their 
absorption of oxygen. Taking identical parcels of seeds, of equal number 
and equal weight, he arrived at the following conclusions : 
1 . Light constantly accelerates the absorption of oxygen by germinating 
seeds. The advantage in favour of light varies from one quarter to one-third 
of the amount of oxygen absorbed by the seeds kept in the dark. 
2. There is a relation between the degree of illumination and the amount 
of oxygen absorbed. The influence of light is very manifest under a clear 
sky and bright sun ; with a cloudy sky it gradually decreases. 
3. The acceleration produced by exposure to light persists for some 
hours after the exposed seeds are in the dark. 
4. The difference in the quantities of oxygen absorbed in light and dark- 
ness are greater in winter than in summer ; hence it would appear that the 
influence of light upon this respiration is more intense at low temperatures. 
In a second communication, M. Pauchon gives the results of a series of 
experiments in which he determined the amounts of oxygen absorbed, and 
of carbonic acid exhaled, by identical parcels of germinating seeds in the 
light and in obscurity, thus ascertaining the different values given by these 
CO 2 
conditions to the fraction -|gp . His experiments were made upon two 
seeds of opposite types — the oleaginous and albuminous seeds of Ricinus — 
and the starchy and non-albuminous seeds of the Haricot. His conclusions 
are as follows : 
1 . The quantity of oxygen absorbed was, as before, always greater under 
the action of light. With the Ricinus the amount of carbonic acid exhaled 
was a little greater in obscurity than in the light; but with the seeds 
of Phaseolus multi/lorus the result was different. 
CO 2 
2. In obscurity the relation was, with the Haricot at least § above 
that ascertained for the Ricinus. With the latter it attains O’ 58 in an 
experiment suspended on the fourth day, and 077 in one lasting five days. 
With the Haricot the relation is 1T4 in four days, and 1*03 after the sixth 
CO 2 
day. The prolongation of the experiments tends to render the relation -q- 
equal to unity, whatever may have been its original value. 
CO 2 
3. Comparing the relation -q- in a single experiment, there is always in 
favour of darkness an advantage of about J in the value of this relation, 
i. e. for the same amount of oxygen absorbed, seeds placed in darkness 
exhale more carbonic acid than those in light — sometimes, indeed, the 
absolute quantity exhaled in light is less than that set free in darkness. In 
the light there is always less carbonic acid exhaled than oxygen absorbed, 
and the reverse is the case in the dark. 
