445 



the epidermis (?) of the under side of one part of the perianth has devel- 

 oped erect, cIub-Hke tubes, at first bent toward one another hke lopped 

 trunks (s), which first had been held together by the brown-walled, swollen 

 epidermis not affected by the stretching. After the epidermis had ruptured, 

 the tubes, which were rather thick walled, deep brown and had lost their 

 contents, separated from one another like sheaves. The process of the 

 over-elongation gradually attacks the deeper and deeper lying parts of the 

 cell and finally advances even directly to the upper epidermis (zc/). At this 

 time the epidermis ruptures and the tips of the perianth tip^ become 

 perforated. 



The first stages of the intumescences have been studied in the ovaries. 

 The first symptoms are a localized change in 

 the epidermal cells, the walls of which are yel- ^ 



lowish brown, and swollen. These cells extend 

 over the upper surface. Beneath these places 



Fig. 84. Cross-section through an intumescence on tlie perianth of Cymbidium 

 Lowi. Upper figure, young stage; lower figure, mature condition. (Orig.) 



O upper side. (' under side, e epidermis, s (upper figure) besrinning of elongation of the sub-epidermal cells, 



J (lower figure) the rupturing of tlie club-like over-eloiigited cells, g vascular bundled. 7ii av meed 



condition of perforation. 



the tissue is perfectly colorless, more closely pressed together and filled more 

 abundantly with protoplasm and oily looking drops. In some of these places 

 a radial stretching has already taken place, which increases up to a diagonal 

 inclination and cross-division. The process gradually extends to the sur- 

 rounding cells, especially to those lying directly beneath the epidermis. The 

 elongating layer becomes strikingly thick-walled and turns coffee brown, 

 while the collapsing, swollen epidermis forms a light yellowish brown cap. 

 The discoloration is accompanied by a process of suberization, and to this 

 probably may be ascribed the fact that the cells, becoming brittle in the still 



1 Sorauer, P., 

 19, p. 115. 



Intumescences an Bliiten. Ber. d. Deutsch. Bot. Ges. 1901. Vol. 



