34 
Notes on Recent Literature. 
numbers of buried germinable seeds at different depths beneath old 
forest Acacias. Thus beneath a tree of A. dealbata, per volume ©f 
eight cubic inches of soil, there were found twenty-eight seeds at a 
depth of three inches, sixteen seeds at nine inches, and three even 
at eighteen inches, all germinable. 
Such provision of hard seeds accounts for some of the recorded 
phenomena ; but as Ewart points out the records of the occurrence 
of meadow seeds in the surface soil of forests rather than more deeply 
buried clearly point to efficient continuous distribution and not to 
longevity prolonged from before the period of afforestation. 
In a final class of cases no credence at all is to be attached to 
sensational assertions of longevity. Here we find the alleged 
germination of wheat from Egyptian tombs and from the granaries 
of Herculaneum, etc. In genuine “ mummy wheat ” the embryo is 
always somewhat perished and has acquired a brownish colour, 
probably the result of slow oxidation. 
We may now pass to some consideration of the fundamental 
question. What is the state of the protoplasm in dormant seeds? 
Are vital processes going on continually though extremely slowly, 
or is all change at a standstill? In the time of Claude Bernard this 
was a burning question in Paris, and in 1861 a Committee of the 
Societe de Biologie reported in favour of the latter view. This 
view was largely based on experiments in which seeds had been kept 
in ether, alcoholic corrosive sublimate, nitrogen, mercury, or a 
high vacuum for a year or two without loss of viability. These 
conditions involve suppression of any gaseous exchange of a respi¬ 
ratory nature, even when no active poison is present. 
Other authors 1 have on the contrary asserted that ordinary dry 
seeds continually take in oxygen and give out C0 2 , though of course 
to a very small degree. 
Becquerel’s recent researches have apparently harmonized and 
explained these contradictions by his discovery that the testa of 
most seeds is quite impervious at a certain degree of dessication. 
Now some observers have worked with seeds carefully dried and 
others with seeds in only their natural air-dry condition, when they 
still contain some 10% of water. 
Obviously if the testa is dry and quite impermeable, then sur¬ 
rounding the seed with ether or alcoholic corrosive sublimate can 
cause no injury. Becquerel has shown that a perforation of the testa 
is all that is required to give a contrary result, and that once these 
noxious substances penetrate to the embryo the seed is killed. 2 
All that former experiments prove is that seeds can exist for a 
considerable time without any gaseous exchange with the environ¬ 
ment. This might still be possible on a theory of immensely 
retarded vitality in which a minute, but continuous conversion of 
the oxygen contained within the testa into carbon dioxide was 
taking place. 
To remove this possibility seeds were perforated and then dried 
completely and kept for two years in a high vacuum. Here there 
1 Van Tieghem et Bonnier; Ann. agronom., 1880, and Bull. Soc. 
bot. de France, 1882. 
a In some seeds, e.%. Ricinus, the testa is fairly pervious, even 
when quite dry, and such are killed by ether, etc. even wheq 
the testa is intact, 
