SECRETARY'S PORTFOLIO. 331 



and the pistils at once supplied with pollen, and not covered up, there would 

 be a strong probability of a cross. Trees are sometimes planted close together. 

 The flowers on the interlocked branches are visited freely by the bees, and 

 pollen is thus carried from one tree to the other. The anther containing 

 pollen can be handled with small forceps, and pollen thus placed where it is 

 desired. The tip of the pistil [stigma) when ready to be fertilized, is usually 

 covered with a sticky excretion. A little honey or syrup can be touched to the 

 tip of the pistil to help hold the pollen in place, though this is hardly worth 

 the labor. The flowers of peaches and plums are essentially like those of 

 cherries. Apples, pears and quinces have five tips of pistils to each flower, 

 surrounded in each flower by about twenty stamens. Raspberries and straw- 

 berries have many pistils and many stamens to each flower. Gooseberries and 

 currants have two pistil tips and five stamens, surrounded by quite small petals 

 and sepals. All of these flowers can be crossed much in the way given for 

 cherries. In all the cases above it is well to leave the specimens covered with 

 sacks until they are ripe. 



Grapes are rather more difficult, and should not be attempted by the 

 beginner, at least without assistance. In most of them the petals stick together 

 at their tips, and come off altogether without expanding. To secure a cross in 

 grapes, it is necessary to lift off the petals and remove the stamens before 

 they are ripe enough to shed pollen. 



It is by no means difficult for any handy person to cross-fertilize wheat or 

 oats. Purchase some fine forceps. Before the stamens are ripe or are thrust 

 out, spread open each pair of chaffs and carefully pick out the three stamens. 

 Have near by another head or spike of the same age of the sort desired to use 

 in crossing. From this take a single plump anther, not yet open, and place 

 inside where the three others were taken out. Let the chaff close up, and pass 

 on to each rudimentary kernel in the spike or head. No paper or muslin sack 

 is needed. A person can cross a spike of wheat in an hour. There are but 

 few people engaged in this crossing of wheat, and, as I shall show, the work 

 is interesting, promising and profitable in more ways than one. 



FREEZING OF THE SAP IN PLANTS. 



In many discussions differences of opinions arise from failure of one side to 

 grasp just what the other means. A good illustration of this is furnished by 

 the following from the pen of Jno. Hovey to the London Garden: Does the 

 sap of trees freeze? This is a question which has been in dispute, and some of 

 your contemporaries here do not believe in the theory. Under certain condi- 

 tions, however, there can be no doubt the sap does freeze, and under others 

 probably not. So far as sugar and starch freeze, just so far a tree will freeze; 

 but the sap does freeze. I have had strong plants of tea roses frozen so hard as 

 to split open the stem and the exuded sap to completely cover the wood with a 

 coating of thin ice; and I cannot doubt that any tree before it has finished its 

 hibernation will freeze when the cold is severe enough. There is a row of Lime 

 trees on Boston Common which freeze so hard in our severe winters as to open 

 the trunk for the distance of twenty feet or more from the ground fully one 

 inch in diameter. I have put my hand in the crack. Yet these same trees 

 in July would show no more signs of the opening than a mere vertical line of 

 extravasated tissue. I have recently read in the papers that trees in the Jardin 

 des Plantes were split from top to bottom by the frost. 



