MISCELLANEOUS: EXPERIMENTAL TERATOSIS 583 



no connection with the ordinary vascular system of the plant 

 (Fig. 451 A leaf, B stem), but are independent growths (parasit- 

 ical implants, so to speak) developing either from scattered hairs 

 or from various other places in the epidermis, especially glands 

 which abundantly dot the surface of the young stems and the 

 very young leaves (Figs. 428Z) and 452X, Y). In this stage 

 they are separated from the vascular cylinder of the stem (Fig. 

 4515) and leaf (Figs. 4olA and 453) by a thick layer of colorless, 

 coarse-celled hypoderm. These embryo plants, or new organ- 

 isms, as they must be considered, develop a vascular system of 

 their own, but those that perish (the vast majority) never suc- 

 ceed in connecting this with the normal vascular system of the 

 parent plant. Those shoots that persist are the ones that have 

 formed a junction with the xylem-phloem of the mother plant. 



11. My experiments show that the surface of this plant, at 

 least above-ground and in early stages of its growth, has, rather 

 uniformly distributed in it, thousands of germinal or totipotent 

 cells, most of which ordinarily remain dormant but which can 

 be shocked into development, if the shock is applied early 

 enough, that is, while the tissues are still very young. These 

 shoots are not the development of preformed buds. They are 

 not branches, but independent organisms. 



12. Not only are such insignificant organs as the scattered 

 petiolar hairs and the base of stem-glands and leaf-glands, as 

 already stated, able to grow out into whole plants, but these 

 are the parts most likely to give rise to the proliferation. In- 

 deed, I suspect that the trichomes and glands are the only parts 

 of the epidermis able to develop these shoots but have not made 

 enough examinations to be able to pronounce definitely. Judg- 

 ing from my experiments, there is germinal tissue at the base 

 of every acicular hair and of every botryose gland. Often sev- 

 eral shoots arise from a single trichome base or its vicinity, but 

 the trichome itself also may give rise to a shoot (Figs. 436C, 



B. Back side of A. 



C. A branch of No. 1, first series, with shocked internode at I. There is a 

 narrow strip of cork in the middle of I. 



These proliferating parts were embryonic, stipule-wrapped tissues on July 24. 

 Photographed October 8, 1918. X 



