18 INDUCTION, DEVELOPMENT, AND PIERITABILITY OF FASCIATIONS. 



Desckii'tion of Plate IV. 



Sciiii-diagratninaiic transverse sections of stet/is; size reduced to tivo-scvenths of given 



magnifications. 



Series i. O. biennis. Successive stages in the development of a groove-fasciation 

 Medullary parenchyma, mp; region of cambium, c; region of outer phloem and 

 stereome ring,^//,/ region of the inner phloem, ///j/ xylem, .ij/ cortex, ^ta/ 

 epidermis, ep. X 44. 



a. Initial appearance of meristem,^^. 



/;. Appearance of supplementary meristems, Wj,w^, ; position of groove,^; thick- 

 walled parenchyma surrounding meristems,//. 



c. Differentiation of secondary bundles, b^ , b.^, b-^, etc.: callus, cl. 



d. Gradual enlargement and increase of secondary bundles; region of outer phloem 



and of stereome ring,///., ; region of inner phloem,/^//,,- xylem,.r)'., /cambium, (.,. 



e. Union of secondary bundles with primary ring. 



f Last stage before complete fusion with primary ring. 

 Series 2. O. crticiata. Development of a fasciation associated with a cylindrical pro- 

 tuberance. Lettering as before. X 18. 



a. Initial appearance of meristem, ni. 



b. Differentiation of secondary bundle-ring, b^,., in the pith. 



c. Connection of secondary bundle-ring with the primary ring. 



d. Fusion of the same. 



e. Beginning of formation of protuberance at k. 



f. Protuberance cut off, /'. 



Series 3. O. biennis. Development of ring-fasciation. X 25. 



a. Appearance of a single meristem, in. 



b. Development of supplementary meristems, //Zj, ;«., , ;//;,, etc. 



c. Differentiation of meristems into ring of secondary bundle-groups, b-^ , b., , A,, etc. 



d. Appearance of lysigenous cavity, ca. 



e. Gradual fusion of secondary bundle-groups. Inner epidermis, ep.,; inner cortex, 



cx<.: outer phloem of secondary ring, ph-^; inner phloem of secondary ring, 

 ///,,• xvlem,;ij._,; pith,//. 

 /. Break in side of ring, making a flat fasciation. 

 Series 4. O. biennis. Four stages of the development of a specimen intermediate 

 between Series i and 3. i\a corresponds with y. The secondary bundle-ring 

 arises in the middle and passes to the side, where it fuses with the primary 

 ring. X 20. 



