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pistils, but has this further peculiarity, that no one of these 
trees bears both kinds of flowers. The Egyptians only 
cultivate the trees that have fruit-bearing flowers. Every 
year they send to Abyssinia, at the proper season, for 
branches covered with the other flowers, and hang them up 
on their own date trees, and thus impregnation takes place. 
When the great Napoleon made his celebrated invasion, 
that people were so much engaged in defending themselves, 
that they neglected to fetch these branches of flowers as 
they had hitherto done. What was the consequence ? 
During that year there was not a single date in Egypt. 
Now Eerns are considered not-flowering plants, and there- 
fore nothing like impregnation is supposed to happen to 
them. This seems strange, as some of them are very large, 
even magnificent forest trees. They also difier from most 
others belonging to this portion of the vegetable world in 
not having a cellular, but vascular tissue, and in possessing 
woody fibre. Hybrids, also, are occasionally produced. In 
flowering plants a hybrid is said to be formed by the pollen 
of one species falling on the stigma of another. Thus if a 
nurseryman has a choice turnip,* and wishes to save the 
seed of it, he is very careful that no other species of the 
genus should blossom near it, lest, as the common saying is, 
the bees should inoculate it, i. e. carry the powder or pollen 
of the one to the stigma of the other, and the seed would 
consequently produce a hybrid or inferior plant. If there 
are then hybrids in Ferns, and experienced gardeners main- 
tain that there are, it is probable that something similar 
occurs to what happens in flowering plants. What seemed 
so likely, has been ascertained to be true by interesting 
experiments. There is, however, this difference, that in 
ordinary cases impregnation takes place before the fruit is 
formed, while in Ferns it is after the production of the 
spores. It appears that when the spores germinate, a thallus 
or leaf-like scale arises. On this scale appear what corres- 
ponds both to the anthers and stigmas in flowers. The first 
are called antheridia, and the second ovules. The dust or 
pollen of the one duly affects the other. If, therefore, we 
suppose that the spores of the diflferent species are near one 
* This is mentioned because there are so many allied species, cabbages, charlock, 
&c., through which hybrids may be formed. 
