NOTES 741) 



with the result that he uuw finds himself on the whole in agreement with the last- 

 mentioned authors. 



252. Volkens : Ber. 8, 1890. 



253. With reference to the ease of Thymus Serpyllum, Stahl (Pflanzen u. 

 Schnecken, p. 3) maintains that the aromatie secretion must at any rate repel many 

 omnivorous animals. In his opinion, the suceess or failure of a single additional 

 enemy may be a matter of the greatest moment to a plant witness the case of 

 Phylloxera and the Vine. Certainly a pest may become very dangerous to a plant, 

 if it confines its attention to that particular species, though this very instance of 

 Thymus shows that plants may continue to flourish in spite of the ravages of more 

 than one specialised pest ; but it is highly improbable that the existence of any 

 species of plant is ever seriously threatened by omnivorous animals. 



Detto (I.e. [250]) considers that the preceding argument is weakened by the 

 fact that only six of the numerous animal foes of Thymus Serpyllum enumerated 

 in the text are specialised. The author, on the other hand, thinks that the existence 

 of as many as half a dozen specialised pests is sufficient proof of the comparatively 

 feeble protective powers of the oil-glands. 



254. Tyndall passed air through cylinders of cardboard, soaked in various 

 ethereal oils, and then determined its perviousness to thermal radiation in each case. 

 By this method, air saturated with the vapour"of ethereal oil of roses was found to 

 absorb 36 times as much radiant heat as ordinary air. Other values obtained 

 by Tyndall were as follows : 



Wormwood oil -11 



Cinnamon ,, ------ 43 



Lemon 



Rosemary 



Camomile 



Cassia 



Anise 



65 



74 



87 



109 



352 



Cf. Focke : Kosmos, 5, p. 412. Detto (I.e. [250]) has advanced some weighty argu- 

 ments against Tyndall's views. 



255. Goebel : Pflanzenbiologische Schilderungen, 2, pp. 232 sqq. Schilling : 

 Flora, 1894. Hunger : Ub. d. Funktion d. oberflachl. Schleimbildungen im Pfianzen- 

 reich (Inaug.-Diss.), Leyden, 1899. 



256. Internal glands. In addition to the above-mentioned treatises by Meyen 

 and Rauter [250], cf. also Frank : Beitr. z. Pflanzenphysiologie, 1868. Von Hohnel : 

 Sitzb. Wien, 86, 1881. De Bary : Coinp. Anat, pp. 201 sqq. Tschirch : Angewandte 

 Pflanzenanatomie, pp. 477 sqq. Id. P.J. 25, 1893. Sieck : P.J. 27, 1895. Lutz : 

 Bot, Centr. 64, 1895. Solereder : I.e. [47]. 



257. G. Haberlandt : Sitzb. Wien, 107, 1898. Detto : Flora, 1903. Porsch : 

 Ost. Bot, Zeitschr. 1903. Id. Verh. Zool. Bot. Ces. Wien, 56, 1906. 



258. Frank : I.e. [256 J. Van Tieghem : Ann. Sci. Nat., ser. V., 16, 1872. Trecul : 

 C.R. 1865-7. F. Thomas : P.J. 4. De Bary : Comp. Anat. pp. 201 sqq. and 404 

 sqq. Mobius : P.J. 16, 1885. Tschirch : Angewandte Pflanzenanatomie, pp. 477 

 sqq. Id. Die Harze u. d. Harzbehiiltes, Berlin, 1900. Id. Ber. 1901. J. Moeller : 

 Zeitschr. allg. Ost, Apotheker-vereins, 1896. Schwabach : Ber. 1899-1900. 



