62 



BOTANICAL GAZETTE 



[JULV 



The region of exit of the roots extends from the base of the stem to 

 about i*^"" above. Bruchmann (3) found that in L, Selago, when the 

 . stem was closely apprcssed to the ground, an earlier exit was favored. 

 The root may bend abruptly and leave the stem at a right angle, 

 or it may run around the stem for a short distance not far below the 

 epidermis, leaving the stem at a tangent; but it is more usual for 

 the root to turn gradually toward the outside of the stem and leave 

 it obliquely. The root hairs which in the ''inner roots'^ develop no 

 further than the trichoblast stage, develop extensively and form a 

 dense mat around the external root (fig. 21). The epidermis, which 

 soon disappears in the '* inner root," is persistent in the external. 

 In an old stem in which the departing roots are numerous and thickly 

 crowded, the cortical tissue of the stem becomes torn and fragmentar}^ 

 Most of it disappears, leaving a brush-like mass of roots with very 

 little cortex between them. 



This investigation was conducted at the University of Chicago 

 under the direction of Professor John M. Coulter and Dr. W. J. G. 

 Land, and arose incidentally in connection with an investigation of 



mm 



I 



The University of Chicago 



2. 



4 



8 



LITERATURE CITED 



I. Brongniart 



ces arbres fossiles: precedees d'un examen des principaux caractferes des 



Lycopod 



Comp. Rend. Acad. Sci. 6:876. 1838 



, Archives du museum d'hist. nat. Paris 1:406-448. 1839. 



Bruchmann, H., Ueber Anlage und Wachstum der Wurzeln von Lycopodien 

 und Isoetes. Jena, 1874. 



, Ueber die Prothallien und Keimpflanzen mehrerer europaischer Lyco- 

 podien. Gotha^ 1898. 



5. Leamtt, R. G., Trichomes of the root in vascular cryptogams and angio- 



c. Best. Soc. Nat. Hist. 31:286-289. 1904. 



6. Nagelt, C. und Leitgeb, H., Bau und Wachstum der Wurzeln, Nageli's 



vvissenschaftlichen Botanik 4: 124. 1863. 



sperms 



zur 



7. Pritzel, E., Lycopodiaceae. Engler und Prantl, Die natiirlichen Pflanz- 



900 



St. Petersburg, 1872. 

 .CHS, J., Textbook of 



Leitbiindel-Krypt 



Eng. ed. Oxford. 1882. 



Schlkctendal, D. and Chamisso 



1830. 



