1899.] NATURAL SCIENCES OF PHILADELPHIA. 117 



the size of the fertile ones. In the paper on the grape above cited, 

 the author traced the successive stages of growth in the fruit by 

 the aid of a powerful microscope. The mother or berry-bearing 

 plant has the power of growth up to a certain stage. Ovarium, 

 ovules and every part advances up to about half the size of the 

 full-grown stage, when it awaits the entrance of the pollen tube. 

 If this tube fails to appear at this stage, the funiculus or neck 

 connecting the ovule with the placenta dies, and this ends all future 

 growth. The grape is a plant having female flowers, male flowers 

 and neuters. It is among the latter that the currants or seedless 

 grapes appear. The ovaries and ovules are perfectly formed, but 

 the stigma is imperfect and will not admit the entrance of the 

 pollen tubes. 



