CELL-CONTENTS AND FORMS OF CELLS. 207 



yield very large amounts of tannin. Nut-galls formed on certain 

 species of oak yield 65 per cent, of tannin. The Japanese galls 

 and Chinese galls formed on the leaf stalks and young branches 

 of some species of Rhus contain about 70 per cent, of tannin. 

 The galls found occasionally on sumach (Rhus glabra), a shrub 

 abundant in North America, yield over 60 per cent, of tannic 

 acid. The tannins obtained from excrescences of this character 

 were at one time called " pathological tannins," to distinguish 

 them from the tannins formed naturally in the living plant, and 

 which were called " physiological tannins/' In the light of the 

 studies on the several tannins this terminology is no longer 

 accepted. 



INCLUSION CELLS AND TANNIN IDIOBLASTS. In a number of 

 plants occur special cells which vary considerably in form and con- 

 tents, but are distinguished by giving reactions for tannin. In- 

 clusion cells were first described by Fliickiger in the fruit of 

 Ceratonia Siliqua. These occur in the form of long tubes, which 

 are easily separated from the pulp, and the yellowish contents 

 are colored blue with solutions of ferrous sulphate or ferric 

 chloride. Recently Hanausek has contributed several papers on 

 the distribution of inclusion cells in a number of different plants. 

 In the leaves of Pistacia Lentiscus he found (Ber. d. d. Bot. Ges., 

 1914, p. 117) that the upper row of palisade cells and the loose 

 mesophyll cells (Fig. 114, A) contain numerous somewhat 

 elongated, transversely striated bodies, which completely fill the 

 cells. These are colored dark green or blackish with ferric 

 chloride and a pale violet with a solution of potassium hydrate. 

 The contents dissolve on heating, changing to a brownish color. 

 They are also partly soluble in concentrated sulphuric acid, and 

 with solutions of vanillin + hydrochloric acid the contents are 

 colored red. They are not completely soluble in hot solutions of 

 potassium hydroxide, there always remaining a small, colorless 

 portion. The inclusions in the date (Fig. 114, B) and tamarind 

 resemble those found in the fruit of St. John's Bread (Ceratonia) 

 and leaves of Pistacia. Inclusions have been found in the seed 

 coat of Pimenta and one or more fruits in the following families : 

 Anonaceae, Anacardiaceae, Ebenaceae, Elaeagnaceae, Leguminosae, 

 Palmse, Rhamnaceae, and Rosaceae. 



