PAPERS ON AGRICULTURE 95 



CONCLUSIONS 



The nitrogen content of forage plants increases with alti- 

 tude. 



No regular changes were noted in the other plant constiu- 

 ents as represented by the approximate analysis. 



The probable cause is the change in habitat of the plants 

 due to change in general climatic conditions. 



THE ARTIFICIAL GERMINATION OF MAIZE 

 POLLEN 



By L. H. Smith and D. I. Adronescu,* University of 



Illinois 



While the pollen of many kinds of plants germinate very 

 well in water or even in moist air, others require the presence 

 of certain substances in solution. A sugar solution offers 

 such a medium in quite a number of species while in other 

 cases this must be either replaced or else combined with some 

 other substance, sometimes organic, sometimes inorganic, in 

 nature. In some instances a decoction of the stigmatic parts 

 has been found to be essential in inducing germination of the 

 pollen. 



Although certain authors have claimed to have successfully 

 germinated maize pollen, attempts to repeat their work have 

 resulted only in failure for us, altho we have tried repeatedly 

 with a considerable number of different substances used as 

 substrata. 



Immersed in water, the pollen grains rapidly absorb moist- 

 ure until they suddenly burst. The same is true in the case 

 of many solutions, although this action is more or less re- 

 tarded. With other solutions, instead of this sudden rupture, 

 the pollen cells were seen in the course of a few minutes to 

 eject long streams or sprouts of protoplasm, often curling and 

 twisting in all directions, and with such force as to throw 

 the pollen grain backward in recoil. These filamentous ap- 



*The data for this report were collected by the junior author in connection 

 with a thesis entitled "The Physiology of th€ Pollen of Zea Mays with Special Regard 

 to Vitality." 



