MISSOURI BOTANICAL GARDEN BULLETIN 45 
after varying lengths of time. About 600 species recorded 
by Ewart were from seed which had been sent out from Kew 
40 years before for a projected botanical garden at Melbourne, 
but were locked up in a cupboard and forgotten. As the re- 
sults of the investigations of these two workers, it was possible 
to make a significant generalization about the type of seed 
which show extreme longevity, namely, that all had exception- 
ally strong and impermeable coverings. Not only are coats 
of such seed impervious to air, but they are likewise im- 
permeable to dry alcohol, ether, chloroform, and similar sub- 
stances. These hermetically sealed seeds, therefore, are able 
to live longer because of protection from external influence. 
Some seed retain their vitality but a few days. Others, if 
properly preserved, will germinate after years and possibly, 
in rare cases, a century or more may pass before they are 
lifeless. In any case a fundamental question concerning the 
state of the living matter in a dormant seed remains to be 
answered. Are vital processes slowly but continuously going 
on within a seed or is everything at a standstill? Originally 
it was believed, because seed could be immersed in various 
toxic substances or kept in a vacuum for a year or two with- 
out loss of vitality, that there could be no gaseous exchange 
between the contents of the seed and the outside. Some in- 
vestigators contended that respiration, that is, taking in of 
oxygen and giving out of carbon dioxide, continually takes 
place in dry seed just as it is carried on in living plants and 
animals. Certain experiments seem to prove that seeds can 
exist for a considerable time without any gaseous exchange 
with the outside world since their walls have become abso- 
lutely air-tight. Hence, if there are any changes going on, 
each cell must be living on its own supplies, and the life of 
the seed is necessarily limited to the length of time required 
to use up such a source of energy. If, on the other hand, a 
dried seed has really entered into a state of ‘‘statie equilib- 
rium’’ in which no change whatever takes place, it should be 
capable of retaining its vitality indefinitely. 
Becquerel has inaugurated an experiment which some day 
may answer the question but unfortunately we cannot antici- 
pate an answer within this century, since time alone can be 
the test. He has prepared seed by perforating their outer 
coats and drying them completely, after which they were 
placed in a high vacuum and deposited with the Bureau of 
