and then leave a wide open micropyle (Fig. 19), This 

 is finally closed into a slit-like fissure between the 

 edges of the outer inter;\iment. 



The (Alter integument is now (juite thick, formed 

 of about eight layers of cells, and is uniform in 

 sti'ucture throughout its thickness. The inner integu- 

 ment is made up of three layers of cells which are 

 very much alike. The epidermal layer of the nucellus 

 has already become slightly different from the under- 

 lying tissue. 



Pollen-tubes artificially grown . 



Pollen taken from open anthers was very readily 

 sprouted in a sixteen per cent, sugar solution, made 

 with tap water, in vhich on'"! and one-half per cent, 

 gelatine was dissolved. The pollen grains first be- 



