PHENOMENA OF PLANT-LIFE. 17 



usually succeeded by four males, so that on such a vine a 

 squash would be produced at every fifth node, if every one 

 should set, which, however, never happens. The impregna- 

 tion of the ovules within the ovary of the female flower 

 requires the deposition of pollen-grains from the anther-cells 

 of the male flower upon the stigma of the former under favor- 

 able circumstances. The stigmatic surface must be in a proper 

 condition to retain and develop the pollen, which must be in 

 a perfect state. Bright, warm weather will doubtless aid in 

 the process, though many observations are still needed con- 

 cerning this subject. The pollen-grains of the squash are 

 large and rough, and of a spherical form, and consist of an 

 outer and inner coating of membrane filled with a proto- 

 plasmic fluid. In the outer coating is a minute orifice, 

 through which, when moistened by the saccharine secretion 

 of the stigma, the inner coating protrudes as a microscopic, 

 structureless tube, which pushes its Way through the tissues 

 of the style and ovary until it reaches the embryo-sac of an 

 ovule, which may then become a perfect seed. This contact 

 of the pollen-tubes with the ovules is essential to the setting 

 of every squash. The transfer of the pollen-grains to the 

 stigmas is usually accomplished by insects whicb fly from 

 flower to flower in pursuit of food. It may, also, be done 

 artificially, and there is reason to believe that the crop 

 of squashes, melons and cucumbers might often be largely 

 increased by attention to thi* matter in out-door cultivation. 

 When grown under glass, fertilization must always be effected 

 by artificial means. 



The pistillate, or female flower, on the twenty-first node of 

 the growing vine, was artificially impregnated with pollen 

 from a staminate, or male flower, on the first of August. 

 The young squash immediately began to enlarge, and-, on the 

 fifteenth of the same month, measured twenty-two inches in 

 circumference ; on the sixteenth, twenty-four inches, and on 

 the seventeenth, twenty-seven. Though the rind of the young 

 fruit was very soft, it was now determined to confine it in 

 such a way as to test its expansive power. In doing this, 

 great care was taken to preserve the health and soundness of 

 every part of the squash, and to expose at least one-half of 

 its surface to the air and. the light. The apparatus for test- 



