op arts and sciences. 267 



Final Conclusions. 



If color and pattern are produced in a purely mechanical manner, as 

 Prof. AVeismanu contends, it ought to be possible to explain and to 

 prove this mechanical manner, if we will go beyond the simple belief 

 that it is so. 



The foregoing review contains all that is known about these ques- 

 tions : — 



1. That some colors of insects can be changed or obliterated by 

 acids. 



2. That two natural colors, madder-lake and indigo, can be pro- 

 duced artificially by the influence of acid on fat bodies. 



3. As protein bodies in insects are changed into fat bodies, and may 

 be changed by acids contained in insects into fat acids, the forma- 

 tion of colors in the same manner seems probable.* 



4. That colors can be changed by different temperature. 



5. That the pattern is originated probably by a combination of 

 oxygen with the integuments. 



6. That mimicry of the hypodermal colors may be effected by a 

 kind of photographic process. 



In comparing these still insufficient data with the statement — that 

 color and pattern are produced in a purely mechanical manner, and 

 are the consequences of natural selection, of adaptation, and of inherit- 

 ance, — we must, if we wish to go beyond belief, directly exclude in- 

 heritance, as after the statement of Professor Weismann himself f it is 

 entirely unknown how inheritance works ; even the question itself is 

 still entirely untouched. We must further exclude natural selection 

 and adaptation, as both are (according to Professor C. Semper $) only 

 able to begin to work after pigment is produced and after a chango 

 of the pattern has begun. 



What is then left to justify our accepting a purely mechanical 

 manner but the simple belief that it is so ? 



I am convinced that color and pattern are produced by physiolo- 

 gical processes in the interior of the bodies of insects. 



* Dr. R. Sachse : Die Chemie und Physik der Farbestoflfe, Kohlenhydrate 

 u. Protoinsubstanzen, p. 288 sqq. Leipzig, 1877. 



t Dr. A. Weismann : Die Dauer des Lebens, 1882 ; and Studien, vol. ii. p. 

 296. 



t Professor C. Semper : Die natiirlichen Existenz-bedingimgen der Thiere, 

 1880. Vol. i., p. 265; vol. ii. p. 232. 



