340 . IOWA ACADEMY OF SCIENCE Vol. XXV, 1918 



Tilia americana, in field, free. 



Prunus padus, under trees, abundant April 10. 



Acer negundo, under trees (campus), abundant May 18. 



Ulmus americana, under trees (campus), a,bundant May 18. 



Ulmus fulva, under trees (campus), abundant May 18. 



Ulmus pumila, under trees (campus), free May 18. 



GENERAL BIBLIOGRAPHY. 



Tourney, James W., Review. The testing of forest seeds: Proc. of 

 the Soc. of Am. Foresters, 11, pp. 91-93. 



Rafn, Johannes, The testing of forest trees during twenty-five years, 

 1887-1912, 1915. 



Tillotson, C. R., Review. Seeding and planting in the practice of 

 forestry: Proc. of the Soc, of Am. Foresters, pp. 448-453. 



Tourney, James W., Seeding and planting in the practice of forestry. 



Pammel, L. H, aiid King, C. M., The germination and juvenile forms 

 cf some oaks: Proc. Iowa Academy of Science, 24, pp. 367-391. 



