AN INVITATION TO DINNER. 341 



So the fern's first course would be water. But dissolved in this 

 potage it would obtain a second article of diet, namely, the mineral 

 constituents of its food. Lime, potash, sodium, flint, and even zinc 

 are found in the plant bill of fare which the botanist compiles. One 

 member of the violet family has so far developed its special tastes in 

 the way of food and feeding, that it will only flourish where zinc is 

 contained in the soil. This Viola reminds one of Professor Caudal, 

 and other eminent diners-out, who never enjoy their entertainment, 

 unless their special brand of champagne, brut, is to the fore. Again, 

 there are certain plants which, having no green colour, live on dead 

 and decaying animal or plant matters. Such are the fungi, of which 

 tribe the mushrooms are good examples. Then we also find plants 

 of higher rank than the fern, which capture insects for their food. A 

 " Venus's fly-trap " closes its leaves on the flies that alight upon them, 

 and eats and digests the fresh insects. A pitcher-plant drowns insects 

 in its hollow leaves, and, allowing them to putrefy, absorbs and grows 

 upon their decaying bodies. It is remarkable, to say the least, that 

 in plants we should find habits to vary in so marked a fashion ; and 

 it is also peculiar to discover that whilst, like some human beings, 

 certain plants eat their food fresh, other plants, like many people 

 we know, seem to prefer their food or game in a " high " condition. 

 The taste for " high " dainties, so far from being an exclusive trait of 

 culture in man, is an actual feature of many higher and lower plants. 

 Even Professor Caudal, in his taste for grouse passe, finds his nearest 

 analogy in the pitcher-plant and the mushroom. 



But we are wandering from the diet of the fern. Its first course 

 was the water, and its second the minerals that fluid contains. 

 Without iron, we know the green colour or chlorophyll of the botanist 

 cannot be developed ; and the analogy between iron in the plant, 

 and that metal as a blood-constituent and as a blood-tonic in our- 

 selves, is too clear to escape notice. The staple article of my fern's 

 food, however, next to water, proves to be a gas called carbo?iic acid. 

 Curiously enough, this gas is that which with every breath we give 

 out from our lungs, and which, naturally or artificially prepared as 

 the case may be, I shall ingest at Smith's dinner party in the spark- 

 ling wines with which our host favours us, and in the milder potash 

 water we may unite in the smoking-room to the stronger " fire-water " 

 of the civilised unit. For us, the carbonic acid in these forms is a 

 luxury, and not a necessity, however ; by the fern and by every other 

 green plant it is imperatively demanded. The green leaves are 

 greedily drinking in this gas, which, if inhaled into our lungs and 

 blood, would quickly asphyxiate us, and which, as a matter of fact, 

 converts an ill-ventilated room into a Black Hole of Calcutta in 

 miniature. But the green plant absorbs the carbonic acid, which, 

 by the way, consists of so much carbon and so much oxygen. The 



