STRONG SEEDS 



Another very curious point about these fleshy fruits (and 

 also ordinary ones) is the strength of the seed inside. It does 

 not look very strong. 



But an orange seed, for instance, will not be in the least 

 injured if you put it between two glass plates and gradually 

 press upon the upper one up to even a pressure of some thirty 

 pounds. Even hemp seed, which seems quite weak, will en- 

 dure a weight of four pounds. It is impossible to break a 

 prune stone, or to injure a date stone, by standing with your 

 whole weight upon it. 



Such strength is necessary because many of these seeds are 

 eaten by birds and ground up in their crops with bits of 

 china, stones, shells, and the like, which the birds pick up just 

 to help them in crushing their food. 



Fruits and seeds would seem to be exposed to some danger 

 when they are lying on the ground. Horses or other heavy 

 animals might tread on them. But the strength of seeds 

 and their shape is such that no harm is likely to accrue. 

 For instance, I arranged a thin layer of garden earth (a 

 quarter of an inch thick) on a glass plate ; upon the earth 

 I placed four hemp seeds; then I put a 58-lb. weight on 

 the top of the seeds. They were not in the least injured, 

 although the seed of the hemp is not a particularly tough one. 

 Under such conditions the seed simply slips into the earth. 



This is made easy for it on account of its shape, which is 

 generally rounded above and below. A transverse section of 

 a seed would be in shape like the arch of a bridge and its 

 shadow in the water, at least in many cases. There are also 

 usually wonderfully thickened cells in the shell or coat of a 

 seed, which makes it tough and strong. 



The following are a few cases of strong seeds or fruits : — 

 Cotton seed bears a weight of 19 to 20 lb.; the hard fruits 



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