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SOME FACTS ABOUT ARUMS. 
One of the greenhouse avoids, Philodendrum bipinnati- 
ficlum, is a plant with handsome foliage, the leaves being 
deeply and doubly cut. Its sheath, which is greenish without 
and white within, swells into a cauldron-shape at the bottom, 
and in this cauldron is contained the ring of female or 
pistilliferous flowers, which, as in other species, are the first 
to open. In a specimen carefully watched by Dr. F. Ludwig, 
these flowers began to expand at noon, and at the same time 
the temperature of the air within the sheath began to rise 
and continued to do so until seven p.m. When the ther¬ 
mometer marked 38°C., and the heat was so great that 
it could be distinctly felt by the hand even at some distance, 
the temperature of the surrounding air was at this time 
only 15°C. As the flowers burst open a strong, fragrant 
scent, something between musk and cinnamon, filled the 
whole house ; and this, in the plant’s own country, would no 
doubt be well understood by the snails as a signal that their 
bed-chamber was comfortably heated and ready for their 
reception. By noon the following day both heat and 
fragrance were much diminished, and the aperture at the 
base of the sheath was entirely closed. When this closed, 
and not till then, the anthers of the upper ring of blossoms 
burst open and discharged their pollen, which hung about the 
spadix in tassel-like threads an inch long, instead of separat¬ 
ing into dust in the more usual manner. 
Now insects could not possibly carry these tassels, but 
they would adhere readily to the moist bodies of snails, and 
in contact with them would be broken up into single grains 
and thus easily carried away. And the snails must crawl up 
the sheath and come in contact with the pollen, because the 
door by which they entered at the bottom is now closed. Go 
they must, moreover, for their hostess has burnt carbon so 
liberally through the night that the cauldron is filled with 
carbonic acid, and they would be suffocated just as surely as 
the glowing match which Dr. Ludwig introduced was 
extinguished, if they stayed. 
The plant has her own good reasons, moreover, for 
wishing to get rid of her visitors. Not only are their 
services required in carrying away the pollen, but if they 
stayed longer they might be dangerous, for snails are greedy 
creatures, and if not dismissed would begin to devour the 
young fruit-germs and other fleshy parts of the plant. 
Many aroids, indeed, allow their hungry guests to feed upon 
the sheaths, which soon cease to be required for the protection 
of the fruit; but in the great majority of species all the green 
portions are so viruleutly poisonous that not the smallest 
