624 SUMMARY OF CURRENT RESEARCHES RELATING TO 



than that of a simple variation, and he proposes to divide these 

 phenomena as follows : — 



(1) Physiological pilosism includes the formation of hairs or the 

 increase in number of these organs over the whole of the parts of 

 certain plants which are normally provided or totally unprovided with 

 them. This phenomenon is most often produced when plants j)ass from 

 a moist medium to a dry soil. It is a fact of physiological adaptation, 

 the limit of the action of which is very confined ; oscillating between 

 glahrism and pilosism unaccompanied by alteration of specific characters. 



(2) Teratological pilosism commences when the specific facies is 

 altered, and attains its maximum when the modifications are so 

 extensive as to originate the notion of a new species. A large 

 number of conditions, capable of producing nutritive disturbances in 

 the j)lant, may bring about this particular pilosism. 



(3) Pilosism hy the punctures of insects, or " balancement organique," is 

 clearly distinguished from the preceding in that, being very localized, 

 it cannot alter the physiognomy of the species. 



Two cases belonging to the second category are recorded by the 

 author. 



For two years Lilium Martagon L. has been affected in almost all 

 the plants by a pilosism of variable intensity. In its fully developed 

 state the flower (always the first part attacked) does not present a large 

 superabundance of hairs on the exterior epidermis of its perianth; 

 but, even in the bud and before opening, the whole parenchymatous 

 tissue of the perianth increases to such an extent that all the cells, 

 considerably enlarged and thickened in their enveloping membrane, 

 become visible to the naked eye. Under the influence of this hyper- 

 trophy, the flower-bud is rolled in on itself, and the lines of contact 

 of the perianth-leaves disappearing in the bud, the latter bursts at 

 several points, disclosing the completely aborted stamens and ovary. 

 Under these conditions the plant is slightly bent on itself, and long 

 hairs are prevalent on the margins of a large number of the verticillate 

 leaves, which have themselves lost their fulness. 



Genista aspalathoides Lam. is subject to a yet more marked 

 pilosism. It especially attacks the young branches, deforming them 

 by condensation and torsion ; it finally alters the whole foliar and 

 floral system. The flowers thus transformed are (1) normal, but 

 smaller and more hairy than in the pure species ; (2) very reduced, 

 and of a cleistogamic appearance, the ovary having only atrophied 

 ovules ; (3) completely aborted, and replaced by a ball of hairs, 

 forming a thick felt. This pilosism, when it invades the plant the 

 first year and is reproduced several times, gives to the species a 

 special facies, on which Moris has bestowed the name of var. confertior, 

 and De Candolle that of Genista Lobelii. It is simply a monstrous 

 variety in consequence of pilosism. 



Fertilization of Alpine Flowers.* — Dr. H. Miiller describes his 

 observations on the relations between Alpine flowers and insects. 



* Miiller, H., ' Alpenblumcn, ihro Befruchlmig durch Insekten und ihre 

 Anpassungen an dieselben.' (8vo, Leipzig, 1881.) 612 pp. (173 figs.). See Bull. 

 Torrey Bot. Club, viii. (1881) pp. 13-14. 



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