Influence of Habitat on Plant Habit. 137 



I have tried t» show that the geueial conclusioiis obtained in 

 the field may be verified botli by statistical comparison in the 

 herbarium and by culture experiments so far as these have been 

 attempted. Tt is not easy to see what else is required to show 

 the dependence of habit upon habitat. Moreover, the evidence is 

 more convincing than it appears at first sight, for each additional 

 example is not merely another probability but it doubles the 

 probability. To prevent misunderstanding I must state first that 

 this work was finished before the appearance of Professor 

 HensloVs Ijook, though I have quoted 5 of the authorities cited in 

 that work. Most unfortunately his work denies the existence of 

 any struggle for existence ; to me it seems as if the struggle is 

 more intense amongst desert plants than it is anywhere else. 



I camiot deny that this reasoning involves the inheritance of 

 acquired characters, but as Professor Weismann himself admits 

 the possibilitj^ of such inheritance (26), although his followers in 

 this country still deny it, this does not affect the results. Even if 

 Professor Weismann still maintained the position which was 

 insisted upon most strongly in his first puViIication, it seems to me 

 that this direct evidence by many independent observers ought to 

 prevail against speculations without any evidence at all. It is 

 perhaps injudicious of me to introduce the name of Professor 

 Weismann at all, for Jager seems to have been the first to speak 

 of the continuity of the Keimplasma and Nussbaum claims priority 

 for the idea that the Keiracellen are immortal (27). 



I should not have mentioned these facts if it were not that, in 

 the discussion following my first paper on this subject, I was told 

 that my facts must be wrong because they did not suit 

 Weismann's theory. 



Literature Cited. 



1. Lindman — Botan. Centralblatt, Bd. 28, 1886, p. 250. 



2. Meigen— Engler's Botan. Jahrb., Bd. 18, p. 394. 



3. Wiesner — Biologie d. Pflanzen Wien, 1890, and Ber. d. 



deut. Bot. Ges., Bd.. 9. 



4. „ —Botan. Centralblatt, Bd. 61 and 63. 



5. Tschirch— Linnea, Bd. 43, 1881. 



6. Volkens — Flora Aegypt., Arab,, Wuste and Jahrb., d. k.k., 



Bot. Gart., Berlin. 



7. Ilenslow — '■' Origin of Plant-structures," London, 1895. 



8. Are.schoug — Engler's Botan. Jahrb., Bd. 2, Heft 5, p. 511. 



