W. H. P., Chicago, III, writes: - "I see that the editor of the Monthly still allows the sap-freezing controversy a place in his columns, although he keeps himself modestly or cautiously out of the arena, generally. I think it might be well if he would insist on his correspondents defining a few things, or better yet, if he would define them himself:

1. What is it that is said to be frozen, and where?

2. What is sap, and what difference is there in it when the tree is growing and when it is dormant in the depth of winter?

3. Is it the freezing of the sap, and the alteration of its constituents that kills, or is it the expansion of the fluid in the act of freezing that bursts the vessels and disorganizes the plant?

4. Is the sap really fluid in well-ripened wood in a perfectly dormant state, or is it so viscous that a great degree of cold will have little effect on it. as in the case of molasses?

5. Is the freezing of the returning sap or the ascending sap equally fatal to the organization?

6. Is it true that the more perfectly the tree or shrub ripens its shoots, relieves its cells, etc, of fluid, the greater will be its power of resistance to frost?"

[Those of our correspondents who believe that "sap" "freezes," can answer these questions if they desire.

For our part it is not at all necessary that a correspondent should agree with the editor in order to have his views find a place in our columns, - nor do we always feel called to criticise views differing from our own. We like to give everybody a free chance to advance or defend his own views. - Ed. G, M.]