g2 ' [September 



to conclude that a powerful action in the development o£ the muscles 

 is in such a case the cause of a greater combustion or oxidation in the 

 neighboring parts. In fact, on the head of a Cicada, on the abdomen 

 of an ^schna, we find similar patterns, in some way mostly represeait- 

 ing the underlying muscles. In the G-omph'ma, the fact is striking, 

 and far more, as the stronger species mostly possess a large dark 

 pattern. There are some very small species which are almost entirely 

 yellow ; there are no small species entirely black. 



Should the fact, w^ith the explanation, be admitted, a step farther 

 in the explanation of the different patterns would be made. I know- 

 very well that in the Odonafa there are patterns which do not agree 

 with my explanations, even some contrary to it, but if some certain 

 facts be explained, there are perhaps more factors still unknown or 

 unobserved. The explanation given for certain facts would still be 

 admissible, or at least not entirely objectionable.* 



The patterns on the wings and elytra could not be the product 

 of the action of muscles, but I believe it to be probable that the 

 sudden rush of blood or even air, by the accelerated circulation" and 

 respiration in the act of transformation may have the same effect. 

 In this way some patterns, otherwise not, explicable, could be under- 

 stood. The eye-spots in the caterpillars of some PapilionidcB have ■ 

 been ascertained by Leydig to be epidermal colors, and I believe that 

 the various kinds of eye-spots in the wings of the imago are also 

 • epidermal colors. If a stream of blood meet a small obstacle just in 

 the centre, a funnel is formed ; if this obstacle be a ring, and behind 

 it another obstacle, we have two or more funnels, one in the other, 

 and the section of them will be circular or elliptical according to the 

 angle at which they reach the surfaces. Such j)atterns in the elytra 

 and wings are formed or preformed at the time when the wing is a 

 sac ; sometimes before the transformation, and here is another cii'cum- 



* So far as I know the literature relating to the phentimena of mimicry, all these related 

 differences are often confused, and I believe that in separating them, and following the views 

 above given, many facts would be better understood, and this interesting subject more easily 

 advanced. 



Besides all the difficulties which oppose a clear and correct view, there is one more which I 

 do not find mentioned, i. e. the so-called color-blindness and the different degrees of it. Prof. 

 B. A. Gould, in his excellent work ' Investigations on Anthropological Statistics of American 

 Soldiers,' has given attention to it in a very remarkable chapter. " Persons who cannot distin- 

 guish ripe cherries upon the tree, or strawberries on the vine, by their color are far more numerous 

 than would be suspected. Serious misunderstandings and even calamities have been reported in 

 the army, resulting from mistakes in the color of green and red light by officers of the signal 

 corps." He gives the statement that usually one in twenty, and m the soldiers examined one in 

 fifty, was subjected to color-blindness. But these numbers show only the extremes, and it is 

 easy to believe that a much gi-eater number are more or less affected with it. In fact, we have no 

 means of measuring this physiological difference : if two persons call something green, and even 

 compare the color with certain known objects, there is no proof at all that they see just the same 

 color. I th'*--' , at it would be prudent, in describing cases of mimicry, especially when they are 

 ».»x+-".^>^<-<- mtt t; to forget that even the best observer may be unaware of this infirmity, and in 

 1 1 T-i irities on color-blindness always state that the greater number of persons have 



changed. Ky-rmity.-ii. a. h. 



