Ramaley: anatomy of onagraceae. 683 



split and become "shreddy," as it is described in the manuals. 

 It is smooth and white in color. 



All the cell walls are extremely thin, and it is only in the 

 outer layers of cells, i. e. those at or near the surface that they 

 are to any extent suberized. In this respect there can often be 

 noticed a gradual transition from phellogen to mature cork. 

 The large cells are usually somewhat bulged at the expense of 

 the smaller ones. These latter may be so greatly compressed 

 that their presence can only with difficulty be demonstrated. 

 The radial walls of the large, as well as the small cells, when 

 viewed in transverse section are mostly curved or wavy, seldom 

 straight. 



In the younger portions of the stem where the cortical tis- 

 sues are still present the phellogen can be recognized as a few 

 layers of thin walled cells having the shape of mature cork ele- 

 ments. 



In most of the species the early development of the cork 

 pushes out the overlaying tissues causing them to peel off. 

 This is not always the case. In Megapterium missouriensis 

 none of the sections examined showed any great development 

 of cork; the cortex was in all cases present. Only three or 

 four layers of immature cork cells could be seen; the inner ones 

 were compressed and not of full size. A peculiarity in the cork 

 of Meriolix serrulata deserves mention. In some of the sec- 

 tions examined numerous sclerotic cells are present, or rather 

 some of the cork cells have very much thickened walls show- 

 ing lamellation. This characteristic is, in many preparations, 

 quite noticeable. 



The average size of the large cells in cross section is perhaps 

 16mik. x 22mik. This oblong character is occasionally not 

 strictly adhered to; in Kneiffia glauca the cells are in outline 

 nearly square. In Galpinsia hartwegii, they are often of quite 

 irregular shape. Whatever differences may be noted in the size 

 of cork cells are not to be regarded as of any taxonomic import- 

 ance, since considerable variation in this respect often occurs 

 even in different parts of the same plant. 



In nearly all cases crystallogenous cells are present in the 

 pericycle; these are usually considerably larger than the ordi- 

 nary parenchymatous elements; their longitudinal diameter is 

 not infrequently 100 to 200mik. or even 280mik., e. g. , Megap- 

 terium missouriensis. 



A rather remarkable feature to be noted in Anogra pallida is 

 the presence of crystal sacs, horizontally placed; i. e. with the 



