82 



A comparison of various leaves bearing intumescences 

 showed that, in different species, hypertrophy is connected 

 with «;er tain cell-layers of the mesophyll. The uppermost 

 layer of the mesophyll in Eu calyptus globulus, e. ro strata . 

 Ficus elastioa. Cassia tomentosa (comiaare figs. 20 A-nri p.i) etc. 

 participate chiefly, ^i found that the cells of the undermost 

 layer hypertrophy exclusively in Epilobium hirsutum . Accord- 

 ing to Sorauer, these take part predominantly in the formation 

 of th| intumescence in Yitis, as 7/ell as in Solanum Lycoper- 

 sicum ^. Sorauer found distended cells above and below in 

 leaves of Solanum florib-gndium . a participation of the whole 

 mesophyll m carnations'^, "and in extreme cases, in Vitis. In 

 many plants; (for example, Pan danus navanicus. Cattleya. Cypri~ 



fedlTjm Xaevi gatum. A r alia palmata. Panax arborescens, Hedera , 

 elix, Oamellia jappnioaj . the elongation of the cells is 

 only very slight, so that no protuberances or only very flat 

 ones ate produced. The diseased leaf then sho?;s yellov/, trans- 

 parent, usually circular spots - a symptom which Sorauer has 

 differentiated from other cases of yellow spotting as "Aurigo" 

 (for literature, see above) , 



(86) We have -spoken only of the mesophyll. In fact, ±n most 

 intumescences, this is the only participating tissue. In some 

 other cases, however, the epidermal cells also are changed. 

 Dale ^ observed swellings of the epidermis on the upper as 

 well as on the underside in H ibiscus vitifolius . and on the 

 under epidermis in Ipomoea (Tig, 2S) , In the d|itumescence of 

 the tomato, mespphyll and epideraiis hypertrophy. 



There remains to be mentioned finally the fact, that in 

 some intumescences not only an elongation of certain cells ele- 

 ments occurs, but also a division of the cells. A case de- 

 S'cribed by Sorauer is especially interesting. In carnation 

 leaves not only the mesophyll cells are stimulated to cross and 

 longitudinal division, but at times the epidermal cells also 

 so that a cell body is formed from them-. Even in intumescences 

 of other kinds, cell division may sometimes take place. These 

 exceptions tc the rule should not prevent our treating the in- 

 tumescences as a unified group nor the finishing of this dis- 

 cussion in the present chftpter. 



Intumescences on th e blossoms are known as yet only for 

 Oymbidium Lowi (according to Sorauer, loc. cit.) 



1. Atkihson: Oedema of the tomato. Rep. Agr. Exp. Sta. , 

 Ithaca, U. Y. , 1893, p. 101. 



S. Compare besides Sorauer, Prillieux, Intumescences s. 1. 

 feuilles des oillets malades. Bull, Sco. Bot. Prance, 1892, T. 

 2XXIZ, p, 370 



3. Investigations on the abnormal outgrowths or intum- 

 escences on Hibiscus vitifolius linn. Phil- Trans. B. , 1901, 

 Vol. CXCIV, p. 163. Compare further by the same author. In- 

 tumescences of Hibiscus vitifolius. Ann. of Bot., 1899, Vol. 

 XIII, p. 6S2 and on certain outgrowths (intumescences) on the 

 green parts of Hibiscus vitifolius, Proc. Camb. Phil. Soc, 

 1900, Vol. X, part IV, p. 192. 



