IX THE MARKINGS OF ORGANISMS 201 



mark the internal attachment of the muscles. These 

 spots are " centres for aggregation of pigment," and 

 have been supposed to indicate the segmentation of 

 the body, and thus, as Dr. M'Cook says, the patterns 

 probably bear a direct relation to the segmentation. 

 The same facts are observable to a much less degree 

 in the cephalothorax, and M'Cook suggests that the 

 annuli round the legs, which occur especially in the 

 neighbourhood of the joints, may be determined in a 

 similar way by the arrangement of the muscles. All 

 this is exceedingly interesting and suggestive, but 

 from a study of other forms, e.g. insects, one would 

 expect to find that the gradual disappearance of 

 marked segmentation in spiders was associated with 

 a profound modification of the coloration. If, as 

 there is reason to believe, coloration and structure are 

 directly associated, then the new structural characters 

 of the body should be reflected in the markings. 

 It seems probable that this really occurs. Thus 

 Argiope argyraspis has on the abdomen two longi- 

 tudinal yellow lines and thirteen unbroken transverse 

 black lines as well as other incomplete ones. Now 

 as the embryos in spiders are commonly supposed to 

 have ten to twelve abdominal segments at most, and 

 as the posterior ones degenerate during development, 

 it is at least unlikely that these transverse bars have 

 a direct relation to segmentation. It seems more 

 probable that we have another instance of the fact 

 that in specialised organisms the process of integration 

 which has so profoundly modified the segmentation 

 has been accompanied by changes in the colour- 

 markings. 



In butterflies, beetles, and other insects with large 



