24 MASSACHUSETTS HORTICULTURAL SOCIETY. 



Within the enveloping organs we come upon an entirely different 

 set of modified leaves — the stamens, each consisting of a stalk or 

 thread, having at the summit the essential part, a case or anther 

 containing pollen. This pollen can escape in several ways ; in the 

 flower under consideration it escapes by a little slit in the anther. 

 The form of the pollen grains is generally spheroidal ; in the 

 cucumber the pollen grains are nearly spherical, and covered with 

 protuberances. In the evening primrose the pollen grains are of 

 irregular form. These various forms were illustrated by the lecturer 

 on the blackboard. 



Owing to their minuteness we have no means of mechanically 

 dividing these grains for examination by the microscope, and they 

 must be broken up by chemical means. We then find that they 

 contain a tiny mass of protoplasm, with a little food consisting of 

 starch and oil. 



Next we come to a pod containing immature seeds or ovules. 

 The ovule of a lily was sketched on the blackboard, and shown to 

 consist of a central nucleus surrounded by integuments. One of 

 the cells of this nucleus is larger than the others, and only partty 

 filled with a substance shown to be protoplasm, similar to that in 

 the pollen grain. Here we have two reciprocals ; by their inter- 

 action is produced a fertilized germ, capable of growth. The 

 lecturer here remarked that he should confine himself to established 

 facts, and not enter upon any debateable ground. 



When a grain of pollen becomes attached to the stigma, or upper 

 part of the pistil, and begins to grow, a very curious phenomenon 

 is observed. This was illustrated b}' a sketch of the pistil of the 

 shepherd's purse, which has a sticky surface at the upper part, and 

 a row of ovules in the ovary below. The pollen grain receives the 

 moisture of the pistil and sends down a tube, or long cell. At first 

 this grows at the expense of the food stored up in the pollen grain 

 itself; but afterwards, like an invading army, which hves upon the 

 country concjuered by it, it receives food as it goes along. The 

 tube extends with greater or less rapidity, and the tip of this long 

 cell passes through the aperture in the ovule, and the contents of 

 the pollen grain are blended with the embryo. Up to this point 

 there is no change in the ovule, and in some plants, such as a few 

 orchids and certain species of the heath family, like llonotropa, it 

 is left in a rudimentary condition. But in a vast majority of 

 instances there is a great change ; in the shepherd's purse and buck- 



