July 14, 1905.] 



SCIENCE. 



39 



stand the primitive and at which end the 

 derived forms ? At any rate, such a limita- 

 tion brings out the better the true condition 

 of our knowledge, for such an arrangement 

 of forms in a series is about the best service 

 that formal morphology can do. This serv- 

 ice is, to be sure, no small one, for it en- 

 hances broad critical comparison and is, 

 therefore, the result of hard work. But 

 the desire to give this arrangement in 

 series a genetic bearing has oftentimes 

 led us to untenable propositions and 

 explanations. Just as we have little 

 ground for assigning the Cupuliferae to 

 a primitive position, so have we as little 

 evidence for regarding the Casuarina also 

 in the same light. The latter have been 

 placed by a recent systematist at the apex 

 of his system because there has been an 

 inclination to find in them a sort of 'miss- 

 ing link' between angiosperms and gymno- 

 sperms. I may, perhaps, mention that I 

 had regarded such a view as incorrect, even 

 before the evidence was adduced by an 

 American botanist (Frye) that Casuarina 

 has evidently nothing which marks it off 

 from other angiosperms. Many of my fel- 

 low botanists have been inclined to point 

 out as a further example of the fruitless- 

 ness of the search for primitive forms those 

 Bryophytes which have been regarded by 

 me as primitive ; and I readily admit 

 that here also we can not point out any 

 conclusive evidence for their primitive posi- 

 tion, but only for a greater or less sub- 

 jective probability. Numerous other ex- 

 amples (as, e. g., the supposed primitive 

 monocotyledons) may be pointed out, 

 which show that the phylogenetic mor- 

 phology has overrated the prospects of re- 

 sults in search for primitive forms, stim- 

 ulating as this has been. 



This may be seen also if we notice the 

 attitude of phylogenetic morphology to the 

 problem, which the old morphology dubbed 

 with the not very fortunately chosen name 



of metamorphosis, and. which historically is 

 that of homologies. Here, also, it may be 

 shown that the problems have remained the 

 same while only the attempts to reach a 

 solution have changed. 



The idealistic morphology believes that 

 all organs of the higher plants may be 

 traced back to caulome, phyllome and tri- 

 chome; it conceived this process not as a 

 real one, but was content with a conceptual 

 arrangement of different plant organs in 

 these categories, which were really nothing 

 but abstractions. 



That thereby the reproductive organs 

 were left entirely out of consideration — 

 these were referred to modifications of 

 vegetative organs — is explained in part by 

 the fact that they occur in the higher 

 plants less frequently as peculiar parts, 

 and often completely disappear in tera- 

 tological growths, which are with pre- 

 dilection turned to account in theoretical 

 considerations; and in part because of the 

 view that for morphology the function of 

 an organ is a matter of indifference, and 

 that accordingly in morphological consid- 

 erations it can have no significance whether 

 an organ has developed as a glandular hair, 

 chaffy scale or as an archegonium, so long 

 as it has developed out of the outer cell- 

 layer of the plant body ! This standpoint, 

 a complex one, indeed, needs no especial 

 discussion more. Let us, on the other hand, 

 see how phylogenetic morphology has come 

 to terms with the problem '^i metamor- 

 phosis. As an example I select a passage 

 from a prominent American work, in which 

 Coulter and Chamberlain express them- 

 selves concerning the leaf structures of 

 flowers as follows : 



While sepals and petals may be regarded as 

 often leaves more or less modified to serve as 

 floral envelopes, and are not so different from 

 leaves in structure and function as to deserve a 

 separate morphological categoiy, the same claim 

 can not be made for stamens and carpels. They are 

 very ancient structures of uncertain origin, for it 

 is quite as likely that leaves are transformed 



