986 



SCIENCE. 



[N. S. Vol. XXIII. No. 600. 



culture of crayfish will be profitable as soon as 

 the market price is greater than the small 

 cost of food, the inexpensive farm and the 

 value of the little labor involved. The intro- 

 duction of the large Oregon crayfish with its 

 attractive colors and large claws might con- 

 ceivably so stimulate the general demand as 

 soon to raise the market value to such a profit- 

 able level. 



E. A. Andrews. 

 Baltimore, May, 1906. 



TWO LETTERS OF DR. DARWIN: THE EARLY 

 DATE OF EIS EVOLUTIONAL WRITINGS. 



Several letters of Erasmus Darwin have 

 lately come into my possession, and two of 

 them seem worthy of publication, if only for 

 the reason that reference to his evolutional 

 ideas seldom occur in his correspondence. In 

 this regard, for example, Charles Darwin 

 states in his introduction to Dr. Krause's 

 ' Erasmus Darwin,' that ' most of the letters 

 [of his grandfather] which he possessed or 

 had seen, are uninteresting and not worth 

 publication.' 



The earlier letter, I may note, has the merit 

 of referring to Dr. Darwin's work on the 

 anatomy of plants, and to his ingenious effort 

 to show closer correspondence between the 

 organs of the higher plants and the higher 

 animals. Indeed, as we know from other 

 sources, he even expected ultimately to find 

 in plants the homologues of the animal nerves, 

 ganglia and sense organs. Accordingly, we 

 are not surprised to find that he refers here, 

 in quite a matter of fact way, to the ' blood ' 

 and the 'two systems' of a plant. And he 

 gives us also a glimpse of laboratory methods, 

 and of his interest in getting in prompt touch 

 with the results of foreign workers. 



The first of these letters is addressed to 

 ' Sir Joseph Banks, Bar'' Soho Square Lon- 

 don.' and is as follows : 



Radbubn 'Mab. 16 — 82 

 Dear Sir, 



I return'd your sixth volum of the Ameenit. 

 aeadem. & thank you for the loan of it. I should 

 have sooner sent it, but hoped to have received 

 another copy of Murray, & also that Dr. Linneus's 

 supplenientum would have been procured from 



abroad, & thence meant to have returned them 

 together. 



Mrs. Blacburn favor'd us with a copy of Murray, 

 but desired it to be returned in three months, 

 which it was to a day; & as I could procure but 

 one other, & our society was not all resident at 

 Lichfield, we were distressed on this account, but 

 are still flatter'd with daily hopes of more copies 

 being imported. I am sorry you say the re- 

 mainder of the supplementum is not likely soon 

 to be had. 



On looking over Malpighi, & Grew, & Hales, 

 the physiology of plants appear'd to me, not to 

 have hitherto been under the attention of any one 

 perfectly acquainted with the animal economy. 

 Last summer I contrived to inject the absorbent 

 system of the Picris with a colour'd liquor; & as 

 the blood of that plant is white, these two sys- 

 tems were beautifully apparent to the eye. On 



reading a manuscript translation of Mr. 



a Sweedish naturalist, I found the authors, I 

 mentioned to you in my last, had made a set of 

 similar experiments; & I had designed to have in- 

 vestigated this subject, so little understood at 

 present, farther during the summer. 



This however I have now laid aside, for perhaps 

 more important, tho' less ingenious occupations; 

 & shall therefore decline giving you the trouble 

 of sending me the books you are so kind as to 

 offer, both in your last, & in a former letter of 

 yours, I am S''. 



with great respect 



your obed'. servt'. 



E. Dabwin. 



The second letter is of livelier interest. He 

 denies having ' stolen ' his ' Botanic Garden,' 

 or of even having heard of its prototype, prob- 

 ably the ' Universal Beauty ' of Brooke (1735). 

 And he modestly predicts of the effect of his 

 evolutional ' conjectures.' Finally, he refers 

 to the ' Zoonomia,' as having been on his work 

 table— or rather ' lain by him ' for * nearly 

 twenty years ' — i. e., since about 1771. That 

 the work here referred to is the ' Zoonomia,' 

 there can be no doubt; he obviously means an 

 extended evolutional work, and, in a letter to 

 a son, dated the following year (cited in the 

 introduction to ' Erasmus Darwin,' above re- 

 ferred to, page 102), he says, that "he is 

 studying his ' Zoonomia.' " It is, of course, 

 well known that this work was long intended 

 for posthumous publication. But the exact 



