74 SOMETHING ABOUT SEEDS. 
gain credence, and with what difficulty they are refuted when once | 
proclaimed. That some seeds do live for a long time cannot be 
doubted, but no such extreme limit is authenticated as that cited 
for the mummy wheat. There are too many opportunities for error 
and even fraud, where a story is received at second hand from the 
Arabs. The largest of the accepted statements look a mite apoc- 
ryphal. With most seeds the principle of life is evanescent, and it 
is with extreme difficulty that many can be transported from one 
climate or country to another. Even those that preserve their ap- 
pearance unchanged and remain suitable for food, are often found 
to have lost their power of germination. It is claimed, and prob- 
ably with truth, that when the thorn-apple (Datura stramonium) 
springs up in a place where it has not been seen before for many 
years, or even during the life-time of the observer, that the seeds 
` have been lying dormant in the soil until some favorable condition 
has caused them to vegetate. So also when weeds, hitherto un- 
known in the vicinity, spring up along the embankments of a 
newly opened railway, or upon the ruins of extensive conflagra- 
tions. But these are only exceptions to the general rule, that to 
insure the vegetation of seed, it is necessary to plant it within a 
limited space of time, and that the preservation of it indefinitely 
is hazardous. The conditions necessary for the retention of vital- 
ity are not as yet certainly known, but it is thought that a partic- 
ular amount of dryness, together with the exclusion of light and 
air, are essentials to success. 
The total amount of seed produced by some plants is very re- 
markable. Linnzeus Says that a single stem of tobacco yields 
forty thousand seeds, and we all know how well provided with 
them are our commonest plants. It follows, then, that while, may 
be, a portion remain as I have said, dormant for a certain time, 
yet many are destroyed by unfavorable conditions, or as food for 
animals and man. We are thus reminded of the suggestive lines 
of Holmes : 
“ Look at the wasted seeds that Autumn scatters 
e myriad germs that Nature shapes and shatters.” 
I have already spoken of the dissemination of seeds and the 
means by which it is effected. We will now examine with the mi- 
croscope the seeds themselves, Those of Stellaria are always 
pretty objects, as are likewise those of the clove pink (Dianthus 
caryophyllus) and other genera of Caryophyllacew. The seed of 
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