30 THE ENTOMOLOGIST. 



I am glad to say that I am no longer almost the only worker 

 in this field. Acute entomologists and excellent experimenters 

 like W. H. Edwards in America, Merrifield and Dixey in England, 

 Standfuss and Brandes in Germany, and younger gifted men of 

 power likeE. Fischer, have devoted themselves to these questions ; 

 and so it is to be hoped, that a deeper insight may be obtained 

 into these phenomena, and at the same time into some of the 

 processes in the formation of a species, and that those points, 

 which at present must remain in the stage of conjecture, at no 

 remote time may be raised to ascertained fact. 



In order to support my views, I have not hesitated to bring 

 forward my interpretation of the facts as they are now presented 

 to the experience of myself and others, at the risk of having to 

 alter much of it later on, as we do not make progress by blind 

 experiment, but only by experiment having a purpose in view ; 

 and for this we require an interpretation of the immediate facts. 



If I have taken my own theory of heredity as a starting-point 

 for theoretic considerations, this is not because I would force it 

 upon the reader, but because at the present time it is the only 

 theory, that has been so far worked out in detail, that it is possible 

 with it to approach the explanation of the phenomena here in 

 question. But a theory, that can be applied to isolated pheno- 

 mena, has already achieved much, as by this means definite 

 formulae are obtained, which can be worked with, and which have 

 their value even if in the future much of the theory should be 

 proved to be erroneous, and should have to be altered. They can 

 then be embodied in the new formulae of the better theory without 

 the progress, which they have brought, being necessarily lost. 



Freiburg, April 30th, 1895. 



Contents. 



I. Experiments and observations on Chrysophanus phlosas. 

 II. Experiments on Pieris napi. 



III. Experiments on Vanessa levana-prorsa. 



IV. Experiments with Fararge egeria and 7neione. 



V. Experiments on the effect of variously-coloured light on Lepi- 

 dopterous pupas. 

 VI. Experiments with Vanessa urticcB. 

 VII. Effect of warmth on hybernating pupae. 

 VIII. General part: theoretic digest of the facts. 



I. Experiments and Observations on Chrysophanus phlceas, L. 



A. Experiments with a Brood from Parents from the South 

 of Europe. 



Dr. Schiemenz, of the Zoological Station at Naples, was good 

 enough, in the spring of 1888, to capture some females of phloeas 

 in the open in the neighbourhood of Camaldoli, and to obtain 

 some eggs. Some of the eggs were reared by himself at Naples, 



