480 



AMERICAN JOURNAL OF BOTANY 



[Vol. 8, 



on mountains 3,000 m. high and in the desert, showed no higher percentage 

 of pollen with starch than the plants growing under the favorable climatic 

 conditions of the tropical rain forest. He does, however, observe that there 

 is frequently a difference in starch content between mature and immature 

 grains. 



Lidforss (1899, p. 306) reports the analysis of sixteen varieties of pollen 

 for nitrogen and P 2 5 . Of these, 1 1 were from anemophilous, and 5 from 

 entomophilous flowers. He found the average nitrogen content of the 

 wind-carried pollen to be 4.63 percent, while that of the insect-carried 

 pollen was 7.49 percent. The P 2 5 showed a similar difference ; the average 

 for the former pollen being 1.76 percent, and for the latter 3.03 percent. 

 Whether or not this represents a real correlation must be established by 

 further observations. 



The relative amounts of protein, fat, sugar, ash, etc., can best be seen 

 by comparison of tables 1-7. It is interesting 'to note, from Stift's analyses 

 of the pollen of three varieties of Beta vulgaris, that the different constituents 

 may vary considerably in the pollen of one species (Stift, 1896, p. 43; 1901, 

 pp. 105-106). 



Table i. Comparison of Pollen Analyses (figures indicate percentages) 



Kind of 

 Pollen 



Date palm 



Cat tail. . . 



Cypress . . 



Hazel .... 



Pine 



Pine 



Beet 



Rye 



Ragweed . 



Ragweed . 



Authority 



Ash 



Carbohydrates 



Vauquelin, 



1802 

 Braconnot, 



1829 

 Church, 



1875 

 Planta, 



1885 



Planta, 



1885 



Kressling, 



189 1 

 Stift, 1896, 



1901 

 Kammann, 

 1912 

 Heyl, 

 1917 



Koessler, 

 1918 



Ca 3 (P0 4 ) 2 



Mg 3 (P0 4 )2 



37o 



3.81 



3-30 



5-5o 



9.18 

 7-13 

 340 



5-39 

 10.60 



Starch Sugar 



85.76 



5.26 14.7 



Saccharose 

 7.06 11.24 



7.40 12.075 



Pentosans 

 0.89 12.26 



0.89 7.27 



25 



Dextrin Sugars 



2.10 2.10 



Pentosans 

 7.26 

 6.8q 



Stoklasa (1896, p. 631) analyzed the pollen as well as various other 

 organs of apple, horse chestnut, and beet, and concludes: 



Das lecithinreichste Organ der ganzen Pflanze aber ist entschieden das Pollenkorn. 



He found in apple pollen 5.86, in that of horse chestnut 5.16, and in that 

 of beet 6.04 percent of lecithin. Heyl (1919 a, p. 672) discusses the chemical 

 "building stones" from which the substance of pollen sperm nuclei may be 



