264 Journal of Agricultural Research vol. xx, No. 4 



SUMMARY 



(1) Unusual excrescences on the roots of a number of different pines, 

 spruces, and other conifers are found to have the structure of lenticels, 

 much enlarged. They are produced in various kinds of soil in the pres- 

 ence of excessive moisture. Hypertrophy may occur on either weak or 

 vigorous plants. Hypertrophy was decreased by top pruning and was 

 increased by root injury. Such overgrowths have apparently not been 

 previously reported on conifers. 



(2) Conclusions of certain writers, based on work with dicotyledons, 

 that excessive soil moisture stimulates lenticel hypertrophy mainly by 

 increasing general sap pressure and that oxygen hunger is of no impor- 

 tance as a stimulus are not supported by the experience here set forth with 

 conifers. Experiments in which the oxygen supply to the roots is varied 

 without varying the water supply are believed necessary to settle the 

 relative importance of these two factors. 



LITERATURE CITED 



1) Atkinson, G. F. 

 1893. oedema of THE tomato. N. Y. Cornell Agr. Exp. Sta. Bui. 53, p. 



77- 108, 8 pi. Also in N. Y. Cornell Agr. Exp. Sta. 6th Ann. Rpt. 1893, 

 p 99-128. 1894. 



2) Buckingham, Edgar. 



1904. CONTRIBUTIONS TO OUR KNOWLEDGE OF THE AERATION OF SOILS. U. S. 



Dept. Agr. Bur. Soils Bui. 25, 52 p. 



3) Cannon, W. A., and Free, E. E. 

 1917. THE Ecological significance of soil aeration. In Science n. s. v. 



45, no. 1 156, p. 178-180. 



4) Coulter, John Merle, Barnes, Charles Reid, and CowlES, Henry Chandler. 

 1911. a textbook OF botany ... v. 2. New York, Cincinnati. 



5) Devaux, Henri. 

 1900. recherches sur LES lEnticellES. In Ann. Sci. Nat. Bot., s. 2, t. 12, 



p. 1-240, pi. 1-6. 



6) Douglas, Gertrude E. 



1907. THE FORMATION OF INTUMESCENCES ON POTATO PLANTS. In Bot. 



Gaz., v. 43, no. 4, p. 233-250. 



7) Haberlandt, Gottlieb. 

 1875. beitragE zur kenntniss der lenticellen. In Sitzber. K. Akad. 



Wiss. [Vienna], Math. Naturvv. Kl., Bd. 72, Abt. 1, p. 175-203. 



8) Hartley, Carl. 



1915. INJURY BY DISINFECTANTS TO SEEDS AND ROOTS IN SANDY SOIL. U. S. 



Dept. Agr. Bui. 169, 35 p., pi. 



9) Hasselbring, H. 



1905. [review of papers on intumescences.] In Bot. Gaz., v. 40, no. 5. 



P- 39o-39 i- 



(10) Klebahn, H. 



1884. DIE RINDENPOREN . . . In Jenaische Ztschr. Naturw., Bd. 17 

 (n. F. Bd. 10), p. 537-S9 2 - pl- I2 - 



(11) Kuster, Ernst. 



1903. pathological plant anatomy. Translation by Frances Dorrance. 

 258 p. [n. p.] Multigraphed. 



