81 



tissues, the "bark of young shoots, the tissues of the leayes, 

 and blossoms, Sorauer^ has treated intumescences especially 

 (84) thoroughly in numerous works, in the last few years other 

 authors have also turned their attention to them. 



Intumescences ^i^e knov/n on the hranches of Eucalyptus yo st- 

 rata. Acacia pendula. Lavat era, trimestris^ Malope grandiflora 

 and others. Here and there, especially on the side eirposed to 

 the sun, the hark cells are elongated decidedly in a radial 

 direction, finally breaking through the epidermis and spelling 

 out as spongy mounds of tissue masses. The cells ox the prim- 

 ary bark participate in the excrescence, the cells of the raed-^ 

 ulary rays in the secondary phloem are also swollen, but only 

 in cases especially severely diseased, so that the formation 

 of intumescences is thus combined with processes of the kind 

 described above. These pustules on young branches do not fur- 

 nish further anything new for our anatomical consideration. 



The intumescences produced on leaves deserve more attention. 

 Here and there on the upper or lov/er surfaces of the blades 

 arise small protuberances, greenidh or vsfoitish pustules of vary- 

 ing height and' extent. The cells, by the growth of which these 

 forms are produced, originate usually in the mesophyll layers, 

 which are elongated perpendicularly to the surface of the leaf 

 (compare, fig. BO) and at times attain a length amounting to 

 two or three times the normal one. At the same time the strong- 

 er their growth, the more com-plete is the destruction of the 

 chlorophyll content, the walls of .-' '^- 1: • i hypertrophied cells 

 are usually delicate, the layer of eyxoplasm thin, the central 

 vacuole large. Intumescences are produced also by distinct 

 (85) kataplastic hypertrophy. The epidermis lying over the out- 

 growing mesophyll is then only raised and slightly distended, 

 as I found in the intumescences of Epilobium hirsutum, or it . 

 is ruptured, as, for example, in the case of Cassia tomentosa 

 (compare fig. 20). In Ficus elastica (compare fig. 21) the 

 lower cells of the many layered epidermis are pressed together 

 by the growing mesophyll cells and the space originally oc- 

 cupied by the former is finally filled entirely with mesophyll 

 cells. The mesophyll no longer adjoins the epidermis in ap- 

 proximately straight lines, but in decidedly curved ones. 



1. Compare especially Sorauer, I. Handb, d. pflanzen- 

 krankh, 1886, 2, Aufl. , Bd.. I, p. 222. II. Ueber Gelbfleckxg- 

 kett. Porsch. Geb. Agrikulturphysik, 1886, Bd. IX, p. 387. 

 III. Weitere Beobacht. uber Gelbfleckigkeit. Ibid., 1890, Bd. 

 XIII, p. 90. IV. Ueb. d. Knotensucht des G^jmmibaumes. Prackt. 

 Ratg. f. Obst-u. Gartenbau-, 1890, Wr. 4. V- Mitteil. aus d. 

 Gebiet d, Phytopathologie II: M©.. symptomatische Bedeutung d, 

 Intumescenzen. Bot. Zeitg. , 1890, Bd. XIVIII, p. 241. VI. In- 

 tumescenz bei Solanum floribundum. Zeitschr, f. Pflanzenkrankh, , 

 189*7 , Bd. VII, p. 122. VII. Intumescenz an Slattern fder Helken) . 

 Ibid., 1898, Bd. GUI. p. 291, S94. VIII. Uber Intumescenzen 

 Ber, d. D. Bot. Ges., 1899, Bd. XVII, p. 456. IX. Intumescenzen 

 an Bluten. Ibid., 1900, Bd. XIX, p. 115. Uypels described in- 

 tumescences on Antabotrys (lotes de pathologie veget. G. R. 

 Soc. Bot. Belgique 1897, T. XXXVI, 2. p. 256), lloack on grape 

 berries (Treibhauskrankheit d. Weinrebe, Gartenflora 1901, 

 Bd. I, 619) , etc. 



