158 STUDIES IN THE EVOLUTION OF ANIMALS 



markings of Murmna tessellata, and others, but one cannot be 

 expected to tackle the whole of creation at once, and the interest- 

 ing spottings and markings of fishes must be left for some future, 

 investigation. By that time ejjperimenters on the spotting of 

 lower animals may perhaps be able to give us something definite 

 as to their cause. 



This I know, that, even in plants, hairs or spines are often' 

 accompanied at their base with spots, and when the hairs disappear 

 the spots remain. Here are a few instances : Begonia argenteo- 

 guttata has spotted leaves, and each spot has a hair, which is the 

 plant armour, while in Begonia Rex the leaves are piebald, that is, a 

 number of spots have become confluent. Some varieties of this 

 remain haired all over, while others have lost their hairs. Then 

 in Begonia maculata the spots remain, but the hairs are suppressed. 



The deposition of derinal plates in animals undoubtedly 

 depended on heredity, the action of nerye-centres, and an available 

 supply of lime-salts, so that, as I have stated further on, when the 

 plates ceased to be developed, from a deficiency of lime-salts in the 

 blood, the nerve-centres, still continuing their influence, would have 

 brought about changes in the pigmentation, which now, in certain 

 cases, picture the plates themselves. 



The main evidence, however, of the Jaguar and Leopard 

 having descended from plate-armoured ancestors is in the resem- 

 blance of their pigment-rosettes to the plate-rosettes of those 

 extinct mammals ; ^ the same nerve-action which gave rise 

 to bone-rosettes was certainly equal to produce pigment- 

 rosettes, from which the hairs grow. That hairs will often grow 

 as soon as there is a part of the skin free from plates is sufficiently 

 proved by the Hairy Armadillo, and some of its congeners. 



^ In the Tring Museum, as already mentioned, there is a Jaguar which, on the flanks, 

 has veiy large polygonal rosettes with nia7iy (from one to six) spots in the enclosed space. 



