386 TEXTBOOK OF BOTANY 



tests under the directions of specialists. When the pollen to which the 

 individual is allergic has been determined, the physician may inject 

 dosages of extracts specially prepared from the offending pollen. In this 

 way complete or partial immunity to the pollen may usually be acquired. 

 As an alternative the sufferer, once having found out what plants caused 

 his discomfort, may — during the tim.e of their pollen production — go to 

 regions where these particular plants do not grow. 



REFERENCES 



Coulter, J. M., C. R. Barnes, and H. C. Cowles. A Textbook of Botany. Amer- 

 ican Book Company. 1931. Vol. 3, pp. 344-393. 

 Gustafson, F. G. Parthenocarpy induced by pollen extracts. Amer. Jour. Bot. 



24:102-107. 1937. 

 Gustafson, F. G. The cause of natural parthenocarpy. Amer. Jour. Bot. 26: 



135-138. 1939. 

 Riley, C. V. The yucca moth and yucca pollination. Third Annual Report, 



Missouri Botanical Garden, pp. 99-158. 1892. 

 Stout, A. B. The flower mechanism of avocados with reference to pollination 



and the production of fruit. Jour. N. Y. Bot. Gard. 25:1-9. 1924. 

 Thompson, J. Arthur. Biology for Everyman. Vol. 2, pp. 1139-1151. E. P. 



Button & Co., Inc. 1935. 

 Wodehouse, R. P. Pollen grains. McGraw-Hill Book Company, Inc. 1935. 



Chapter VI. 



