CELL-CONTENTS AND FORMS OF CELLS. 227 



vary in length and outline, being either spherical, ellipsoidal, sac- 

 shaped (Fam. Bixaceae), or branched (Fam. Meliaceae). The 

 contents may be in the form of distinct globules adhering to the 

 wall (or in dried material may be in the form of amorphous 

 masses), varying in color from colorless to yellowish or even dark 

 brown. In the secretory cells of certain plants of the Lauraceae, 

 Magnoliaceae, Canellaceae, Aristolochiaceae, and Piperaceae the 

 secretory contents are enveloped by a thin-walled sheath, con- 

 nected with the cell-wall by means of a stalk. The internal glandu- 

 lar hairs occurring in the rhizome of Dryopteris and in Pogoste- 

 mon Patchouli may be included among secretory cells, although 

 they project into the intercellular area rather than into the cells. 

 The cell-wall of the secretory cells not infrequently gives a dis- 

 tinct reaction for suberin. 



Elongated secretory cells or sacs, resembling tannin-idioblasts, 

 and with diverse contents varying from resin to latex-like sub- 

 stances or tannin-like masses, are distributed in the cells of the 

 pith, bast, and pericycle of the stem and occasionally in the larger 

 veins of the leaves of some of the genera of the following families : 

 Anacardiaceae, Berberidaceae, Caprifoliaceae, Compositae, Crassu- 

 laceae, Euphorbiaceae, Lecythidaceae, Leguminosae (very widely 

 distributed and with diverse contents), Menispermaceae, Monimi- 

 aceae, Myristicaceae, Passifloriaceae, Polygonaceae, Rosaceae, and 

 Rubiaceae. 



Solereder also states that similar elongated sacs with brownish 

 contents are observed in the epidermal cells and occasionally in 

 the upper layers of mesophyll of one or more of the genera in 

 the following families : Crassulaceae, Euphorbiaceae, Geraniaceae, 

 Moraceae, Saxifragaceae, and Violaceae. 



2. Secretory cavities are either spherical or ellipsoidal in shape 

 and the contents vary from oily or resinous to gum-like or tannin- 

 like masses. The mode of development of the cavities, as to 

 whether schizogenous, etc., is usually not considered, as this fact 

 is not easily determined in the mature tissues. \Yhen occurring 

 in leaves the cavities give rise to transparent dots or glandular 

 punctate areas. They are also found in the pith and primary 

 cortex of quite a number of plants. 



There are a number of special forms of secretory cavities, the 



