

4A 



THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



in the several genera and species of the vegetable 

 kiugdom. 



In animals, as we have seen, color is greatly 

 influenced by the need of protection from, or of 

 warning to, tbeir numerous enemies, and to the 

 necessity for identification and easy recognition. 

 Plants rarely need to be concealed, and obtain 

 protection either by their spines, their hardness, 

 their hairy covering, or their poisonous secretions. 

 A very few cases of what seem to be true protec- 

 tive coloring do, however, exist, the most remark- 

 able being that of the " stone mesembryanthe- 

 mum," of the Cape of Good Hope, which in form 

 and color closely resembles the stones among 

 which it grows ; and Dr. Burchell, who first dis- 

 covered it, believes that the juicy little plant thus 

 generally escapes the notice of cattle and wild 

 herbivorous animals. Mr. J. P. Mansel Weale 

 also noticed that many plants growing in the 

 stony Karoo have their tuberous roots above the 

 soil, and these so perfectly resemble the stones 

 among which they grow that, when not in leaf, it 

 is almost impossible to distinguish them {Nature, 

 vol. Hi., p. 50V). A few cases of what seem to be 

 protective mimicry have also been noted, the most 

 curious being that of three very rare British fungi, 

 found by Mr. Worthington Smith, each in com- 

 pany with common species, which they so closely 

 resembled that only a minute examination could 

 detect the difference. One of the common species 

 is stated in botanical works to be "bitter and 

 nauseous," so that it is not improbable that the 

 rare kind may escape being eaten by being mis- 

 taken for an uneatable species, though itself pal- 

 atable. Mr. Mansel Weale also mentions a labi- 

 ate plant, the Ajuga ophrydis, of South Africa, as 

 strikingly resembling an orchid. This may be a 

 means of attracting insects to fertilize the flower 

 in the absence of sufficient nectar or other attrac- 

 tion in the flower itself ; and the supposition is 

 rendered more probable by this being the only 

 species of the genus Ajuga in South Africa. 

 Many other cases of resemblances between very 

 distinct plants have been noticed — as that of 

 some Euphorbias to Cacti ; but these very rarely 

 inhabit the same country or locality, and it has 

 not been proved that there is in any of these cases 

 the amount of inter-relation between the species 

 which is the essential feature of the protective 

 " mimicry " that occurs in the animal world. 



The different colors exhibited by the foliage 

 of plants, and the changes it undergoes during 

 growth and decay, appear to be due to the gen- 

 eral laws already sketched out, and to have little, 

 if any, relation to the special requirements of each 



species. But flowers and fruits exhibit definite 

 and well-pronounced tints, often varying from 

 species to species, and more or less clearly related 

 to the habits and functions of the plant. With 

 the few exceptions already pointed out, these may 

 be generally classed as (((tractive colors. The 

 seeds of plants require to be dispersed, so as to 

 reach places favorable for germination and growth. 

 Some are very minute, and are carried abroad by 

 the wind, or they are violently expelled and scat- 

 tered by the bursting of the containing capsules. 

 Others are downy or winged, and are carried long 

 distances by the gentlest breeze. But there is a 

 large class of seeds which cannot be dispersed 

 in cither of these ways, and are mostly contained 

 in eatable fruits. These fruits are devoured by 

 birds or beasts, and the hard seeds pass through 

 their stomachs undigested, and, owing probably 

 to the gentle heat and moisture to which they 

 have been subjected, in a condition highly favor- 

 able for germination. The dry fruits, or capsules 

 containing the first two classes of seeds are rare- 

 ly, if ever, conspicuously colored, whereas the 

 eatable fruits almost invariably acquire a bright 

 color as they ripen, while at the same time they 

 become soft and often full of agreeable juices. 

 Our red haws and nips, our black elderberries, 

 our blue sloes and whortleberries, our white mis- 

 tletoe and snowberry, and our orange sea-buck- 

 thorn, are examples of the color-sign of edibility ; 

 and in every part of the world the same phenome- 

 non is found. The fruits of large forest-trees, 

 such as the pines, oaks, and beeches, are not 

 colored, perhaps because their size and abundance 

 render them sufficiently conspicuous, and also be- 

 cause they provide such a quantity of food to such 

 a number of different animals that there is uo 

 danger of their being unnoticed. 



The colors of flowers serve to render them 

 visible and recognizable by insects which are at- 

 tracted by secretions of nectar or pollen. During 

 their visits for the purpose of obtaining these 

 products, insects involuntarily carry the pollen 

 of one flower to the stigma of another, and thus 

 effect cross-fertilization, which, as Mr. Darwin 

 was the first to demonstrate, immensely increases 

 the vigor and fertility of the next generation of 

 plants. This discovery has led to the careful 

 examination of great numbers of flowers, and the 

 result has been that the most wonderful and com- 

 plex arrangements have been found to exist, all 

 having for their object to secure that flowers 

 shall not be self-fertilized perpetually, but that 

 pollen shall be carried, either constantly or occa- 

 sionally, from the flowers of one plant to those of 



