710 



SCIENCE. 



[N. S. Vol. XXII. No. 570. 



ants in having the power of feeding by re- 

 gurgitation and of forming polydomous colo- 

 nies. These conditions merely serve to link 

 the Ponerinse more closely with the Myrmi- 

 einse, Camponotinag and Dolichoderinse. Dr. 

 Cook destroys the value of his own observa- 

 tions by continually using them in support of 

 his perverse speculations. I can see no reason, 

 therefore, for revising my opinion in regard 

 to the taxonomic and economic status of the 

 kelep as expressed in two previous papers in 

 this periodical.^ Apparently the harder Dr. 

 Cook works to confer exceptional attributes on 

 the kelep, the greater becomes its similarity to 

 other ants, especially to the relatively un- 

 plastic Ponerinse, and hence the less promising 

 it becomes as a subject for agricultural ex- 

 periment. 



The sole result, which, in my opinion, we 

 had a right to look forward to, from all this 

 Corybantic enthusiasm over the introduction 

 of an exotic ant into the United States, was 

 not the protection of the cotton plant from 

 the attacks of the boll weevil, but the produc- 

 tion by some well-trained entomologist of a 

 carefully written and illustrated memoir on 

 the structure and habits of a ponerine ant. 

 Under the circumstances and with the funds 

 and facilities at its disposal, this lay well 

 within the competence of the Bureau of Ento- 

 mology, and may, in fact, be actually under 

 way in the promised report. But assuredly 

 Dr. Howard is not to be congratulated on the 

 kelep articles hitherto published under the 

 auspices of his bureau. We are accustomed 

 to receiving much better work from that 

 quarter. William Morton Wheeler. 



ISOLATION AND THE ORIGIN OF SPECIES. 



President Jordan's paper ' The Origin of 

 Species through Isolation ' ^ has been read by 

 me with much interest. The following para- 

 graph may be quoted as the caption under 

 which he writes : 



In nature a closely related distinct species is not 

 often found quite side by side with the old. It 

 is simply next to it, geographically or geologically 



^ Science, September 30 and December 2, 1904. 

 1 Science, II., 22 : 545-562, November 3, 1905. 



speaking, and the degree of distinction almost 

 always bears a relation to the unportance or the 

 permanence of the barrier separating the supposed 

 new stock from the parent stock. 



It appears to me, however, that the case as 

 stated by him can find scant support of the 

 botanists, to whom it is, I think, easier to 

 find exceptions to the rule, than facts in sup- 

 port of it. The question is, of course, a very 

 complicated one and all who embark on a dis- 

 cussion would fain sound the ' ohligato ' of 

 Leonard Stejneger, ' so far as I know.' A few 

 instances drawn at random will sufiice at least 

 to throw a reasonable but large doubt upon the 

 factor of isolation and the extent of its effects, 

 as stated by President Jordan, at least so far 

 as plants are concerned, and this doubt should, 

 I believe, obligate us to put the caption cited 

 above into the form of an open question. 



Lycopodium complanatum L. and L. iris- 

 tachyum Pursh are two very distinct but 

 closely related species of club-mosses occupy- 

 ing the same range. If we attempt to con- 

 struct a theory of their origin we are com- 

 pelled to regard them as genetically related, 

 whatever the mode of origin may have been. 

 These species . often grow intermingled in the 

 same habitat, and it was the contrast which 

 they presented under such conditions which 

 forced me to examine them with great care 

 and finally to decide upon their distinction.^ 

 And if, as has been urged, our eastern North 

 American plant, L. complanatum, is not the 

 true European species, the case is strengthened 

 rather than weakened. 



In the deserts of the southwest are to be 

 found numerous closely related species of 

 cacti, especially of the genus Opuntia, occupy- 

 ing the same habitats and, perhaps, the same 

 ranges. It would be difficult to apply the 

 principle of isolation to these. As an example 

 I may say that there are two distinct but 

 closely related species of the prickly pear type, 

 which I may not, in the present state of their 

 taxonomy, presume to name, distinguishable 

 by their fruits, which are in one species 



- Lloyd, F. E., ' Two Hitherto Confused Species 

 of Lycopodium.'' Bull. Torrey Botan. Club, 26: 

 559-567, November 15, 1899. 



