38(3 PEOVISIONAL HYPOTHESIS Chap. XXVII. 



Hairs occasionally appear in strange situations, as " within 

 the substance of the brain." 65 Certain breeds of sheep bear 

 a whole crowd of horns on their foreheads. As many as five 

 spurs have been seen on both legs of certain Game-fowls. In 

 the Polish fowl the male is ornamented with a topknot of 

 hackles like those on his neck, whilst the female has a top- 

 knot formed of common feathers. In feather-footed pigeons 

 and fowls, feathers like those on the wing arise from the 

 outer side of the legs and toes. Even the elemental parts of 

 the same feather may be transposed ; for in the Sebastopol 

 goose, barbules are developed on the divided filaments of the 

 shaft. Imperfect nails sometimes appear on the stumps of 

 the amputated fingers of man ; 66 and it is an interesting fact 

 that with the snake-like Saurians, which present a series 

 with more and more imperfect limbs, the terminations of the 

 phalanges first disappear, " the nails becoming transferred to 

 " their proximal remnants, or even to parts which are not 

 " phalanges." 67 



Analogous cases are of such frequent occurrence with plants 

 that they do not strike us with sufficient surprise. Super- 

 numerary petals, stamens, and pistils, are often produced. I 

 have seen a leaflet low down in the compound leaf of Vicia 

 sativa replaced by a tendril ; and a tendril possesses many 

 peculiar properties, such as spontaneous movement and irrita- 

 bility. The calyx sometimes assumes, either wholly or by 

 stripes, the colour and texture of the corolla. Stamens are so 

 frequently converted into petals, more or less completely, that 

 such cases are passed over as not deserving notice ; but as 

 petals have special functions to perform, namely, to protect 

 the included organs, to attract insects, and in not a few cases 

 to guide their entrance by well-adapted contrivances, we can 

 hardly account for the conversion of stamens into petals merely 

 by unnatural or superfluous nourishment. Again, the edge of 

 a petal may occasionally be found including one of the 

 highest products of the plant, namely, pollen ; for instance, 



65 Virchow, ' Cellular Pathology,' to me. 



I860, p. 66. 67 Dr. Ftirbringer, 'Die Knochen 



66 ' Miiller's Phys.,' Eng. Translat., etc. bei den schlangenahnlichen 

 vol. i., 1833, p. 407. A case of this Sauriern,' as reviewed in 'Journal of 

 kind has lately been communicated Anat. and Phys.,' May, 1870, p. 286. 



