' i84 



learn from Mr. Boll. And what was that? I had opened a correspon- 

 dence with him on the same subject late in winter '75-'76. His first 

 letter in reply is before me (the first I ever received from him) dated 

 2oth February, 1876, and it reads thus: " Colias Chrysotheme is now 

 tolerably abundant, and I intend to make a large collection of it up to 

 the larger Eurytheme, so that it will be very hard to determine in re- 

 gard to these two species where Chrysotheme {Keewaydin) ends and 

 Eurytheine begins. The latter appears the latest, and I venture the 

 conjecture that it must come from the autumn eggs (that is, from 

 Eurythcme eggs of the previous year) " or the first forms of Chryso- 

 theme emerging in the spring." (At that date Mr. Boll had not dis- 

 tinguished Ariadne, and never did till I pointed it out to him.) He 

 continues, " the caterpillars will now soon appear upon the clover, 

 and I hope to find a multitude of them." That shows that in Febru- 

 ary, 1876, he knew nothing of the connection, from breeding, between 

 these forms, though he might conjecture that Eurythetne must be the 

 product or its own form of Keewaydi/i, or joint Keewaydiii and Ariadne, 

 which together he calls Chrysotheme. Mr. Boll never obtained eggs 

 from one of these forms, and from eggs bred the larvae. All he did was 

 to search the clover for caterpillars. These, of course, came from eggs 

 laid by different females, but of what type no knowledge could be 

 possible. 



I received the next letter, written May 23, 1876, saying: "This year 

 I have had some Eurytheme caterpillars that look exactly like those 

 of Chrvsotheme, and am confident that the two species are the same, 

 the difference being owing to season." He had found larva which 

 gave Eiu-ytheme butterflies, and these larvae looked like other larvae 

 which had given Keewaydin butterflies, is plainly the meaning there. 

 His published paper shows that he never did obtain eggs, or caterpil- 

 lars proceeding from Eurytheme, even on the clover, so far as he 

 knew. 



On the 26th of November, 1876, the third letter: "I had worked 

 out a letter on the dimorphism and variation of a number of N. Am. 

 butterflies, which was presented by my agent in Europe during Sep- 

 tember, before the Assn. of Nat., and found general interest." The 

 paper itself says nothing about having bred any of the forms from the 

 (tg%, but these are the words: "From November to May, 1 often found 

 caterpillars and butterflies together. The former showed no trace of 

 difference either in color or markings, except that they were found 

 somewhat larger in April; but the butterflies, on the contrary, differed. 

 I caught and bred a number of the latter, No. 1-15 of the collection, 

 from November to the end of February," etc., and he goes on to de- 

 scribe what is the form Ariadne. Afterwards, he says that 1-15 are 

 Ariadne. " Nos. 16-19 were t^^ken in March; 20-25 were taken in 

 April; 26-31 in May; 32, 33 in the last days of June." By the paper, 

 then, it appears that Mr. Boll found caterpillars from November to 

 the end of February, and they gave Ariadne butterflies; and not a 

 word is said of obtaining other forms, or butterflies from caterpillars, 

 even found ones I gave a full abstract of Mr. Boll's paper in my 

 text, and added that his conclusions as to the existence of the three 



