In the second place it fills all interstices where sap would collect.
In the third place it provides an airtight covering so that the free sap pressures, negative and positive, under different temperatures, will be analogous in stock and scion. When there is low sap pressure we assume that some of the sap may be drawn out of the scion. This airtight covering prevents that.
In the fourth place it provides a translucent covering, which allows action by the actinic rays of light, which brings the chlorophyll into activity. All plant growth is conducted under the influence of chlorophyll, and the actinic rays of light activate this. Consequently, I seemed to have a perfect grafting material in this Parowax, which we may find in any grocery store. In my locality this wax worked perfectly and, theoretically, nothing more was to be desired. It melts at 125 degrees farenheit.
I have brought with me a specimen of a pear tree that I grafted in this way in July of this year. You will see that the Parowax covering is still complete. The new shoots have grown about eight inches since July 1, and I do not see how you could imagine anything more perfect than this specimen, from which I wrote my description in the book. As a matter of fact it is by the use of the paraffin method that I seemed to have solved the very great problem of making it possible for anybody to graft anything, and at any time of the year. The most difficult thing to graft is the shagbark hickory, and we have even done that every month of the year, except December and January. This year we are going to try those months, for I believe that the hickory tree may be grafted any month of the year.
Now the point of my remarks will relate to different kinds of paraffin. This Parowax, which melts at 125 degrees farenheit, will be satisfactory in the north temperate regions. We may raise the melting point ten degrees, if we like, by the addition of the carnauba wax, which, however, is highly crystalline. A crystalline wax is not desirable because it cracks and permits the air to enter and we have a desiccation of the scion. The Standard Oil people will furnish paraffin with a melting point of 138 degrees, and that will cover all of our needs for hot countries. But in getting paraffins that melt at 136, 137 or 138 degrees we have a rather definite crystalline element. Mr. Bixby has suggested the use of the earth wax which is mined in Australia. It is really a fossil paraffin and is not so granular. I found that it is not to be had in this country at the present time, however, although various dealers told me that they had it, and I obtained from a firm in New York City a misbranded specimen called "Ozokerite," which they said is a technical term for this particular fossil paraffin. But it was nothing of the sort; it was something they had made up for themselves. Mr. Bixby kindly gave me a pound or so of the real "Ozokerite," so I had the genuine thing to experiment with. We may then settle the question of obtaining paraffines which have a high melting point, by knowing that they may be obtained from any of the Standard Oil people.
Knowing that we must have, in addition, the elastic feature, I found one man who had succeeded by adding something to a high melting-point paraffin. He said that it was a secret, but I soon found that it would be no secret to a bee. It would seem, then, that this quality in beeswax would be valuable, since the secret formula from this same dealer has little more than beeswax in it. Beeswax is a different kind of organic product from paraffin and I would not expect them to mingle naturally when in melted solution, but apparently they do. You will find that the specimens which contain this wax are very smooth to the touch, and apparently are more homogeneous than paraffin.
The subject for experiment then, for members of this audience, is that of finding some substance that may be added to give elasticity, but which will not change the melting point. In the South we may require in addition something to whiten our paraffin. Some men in Southern California wrote me that they had fastened white paper about each graft and put a rubber band over it. I suggested this plan to one or two men in Australia and in Ceylon, who had complained about the melting of the Parowax, and I have not yet received their replies. I have been trying, however, to simplify things in the way of grafting. In addition to the elasticity that we need, we must have whitening, and for this purpose we must add something that will not be poisonous to the tree but will mix with the paraffin readily and give a white paraffin, which will interfere somewhat with the actinic light. I have found that carbonate of lead will mix well with paraffin. Carbonate of zinc will also mix well. They are both heavy, so heavy that they need a certain amount of stirring. A lighter substance is citrate of zinc, which will give elasticity, and which will probably also give a white effect. It melts with the paraffin and, being neutral, it will do no harm to the tree.
I have given you an outline on which I wish discussion, for I hope to get from this audience the information and suggestions that will enable me to make my experiments in the right way so that by next spring we may have no further need for discussing the question as to the correct paraffin method in grafting.
MR. BIXBY: There is another wax that is not so crystalline as the Parowax, and that is Candelilla, which is produced in Texas and New Mexico. It may be obtained from the wax importers in New York City, not from the Standard Oil Co., but the importers. I will find out just where it is from. I can easily get samples. Its melting point is not so high as Parowax, but it is much higher than any of the other waxes.
DR. MORRIS: Then by mixing it with the high-melting point waxes, those of about 138 degrees, we might get good results.