Instructions for Making Capillary-Dynamic Tests

THE PAPER:

This chapter is added for the guidance of anyone who wishes to try examining plant saps by capillary-dynamolysis.

a) The same sap will produce the same fundamental forms in every filter paper. In hard paper they will be smaller, more restricted, in soft paper bigger, freer, than in a medium paper. Series made for comparison should always be made with the same paper. The test made in the book that I have used Whatman Nr. 1

b) Direction. The paper should be used so that the direction of the stronger capillary attraction is the same in all pictures. the simplest way of finding this is to let a drop of water fall on an upper corner of the paper. The water will spread to an ellipse, the length of which indicates the stronger direction.

c) Cutting. In order to prevent the edges touching when the paper is rolled to a cylinder, cut a narrow strip from the right hand side up to about an inch from the top. Use a pattern for this, so that the final width for each cut paper remains the same.

d) Rolling. The paper can be rolled adequately between the two sides of a small roller towel. Checked cloth is useful because the paper can be placed easily square to the edges. Put a rod through both ends of the towel, and holding one in each hand, draw it sharply once or twice downwards over the edge of a table. the paper will then be rolled enough to stand alone. Treat each sheet alike, then fasten at the top with a paper clip. A small machine is used here to ensure constant conditions, but the method described is practical for the amateur

THE GLASS:

Glass dishes that are specially made to fit the rolled papers are used. They allow complete absorption of the measured quantities, difficult to achieve with a petri dish. (you can have Pyrex dishes custom made from any laboratory glassware supplier, like Kontes or Reliance Glass. If you do not want to incur the expense you can use a petri dish, you may have to use a larger piece of filter paper and more sap/metal solution to compensate.)

DUPLICATE TEST:

It is worth while to make at least two pictures with each sap and reagent. When sudden changes in form type or coloring appear, or remarkable forms occur in all the papers, mistakes and paper faults can be discounted. The later are very rare in good paper, and in any case they only discolor small patches without obstructing the capillary absorption.

STORING THE TEST:

The pictures are best stored by laying them in booklets of firm paper and keeping them in the dark. The most important thing is to keep test made with different metal solutions apart, in different booklets, even on different shelves. Some reagents attack others, spoiling the pictures made with them. For example test made with goldchloride and mercury chloride take the color out of pictures developed with silver nitrate, even when a sheet of paper lies between them.

THE ROOM:

The temperature and humidity in the room should be kept as constant as possible. Water can be kept boiling, and large uncovered dishes filled with water that can evaporate slowly will help if the atmosphere is dry. Koliskos lab kept a 78% humidity temp of 68 F. It is best to darken the windows. Daylight will reduce the silver reagent quickly to the detriment of the pictures. Goldchloride is not as sensitive it will suffer from strong sunlight. The colors become harsh, above all where the light falls for long.

EXTRACTION OF THE SAP:

Clumps of soil adhering to roots, bulbs etc. should be removed before these are wiped clean with a damp cloth. Do not wash in a way that allows water to be absorbed. Wet leaves should be dried, others wiped clean. Weigh the parts required, allowing about one gram of plat part for each picture to be made from 50% extract. The parts should be torn into small pieces, or where necessary cut with a stainless knife. This helps the destruction with pestle and mortar. Begin with a small quantity and beat with light firm strokes of the pestle until the plant structure is broken down. Add small quantities and repeat till the parts are unrecognizable in the pulp, except fibbers that cannot be destroyed. Avoid rubbing with the pestle.

CONCENTRATION OF THE SAP:

Any concentration that the paper will absorb can be used. Some plants give a 100% extract that will rise. The concentration chosen will depend on the condition of the pure sap, on the amount of plant substance available and on the aim of the experiment. A 50% extract has proved suitable for many plants. This so-called 50% is obtained by adding equal; weight (volume) of distilled water to the plant pulp. It need not be left to stand: sap pressed out almost at once shows more formative power in the test than when it is extracted after some time. Moisten a linen cloth with distilled water, wrap the pulp in it and press the sap out. If more than one person works on the same experimental series, it is advisable to use a small press set at a constant pressure to extract the sap.

THE EXAMINATION OF VISCOUS SAP:

Highly viscous saps can scarcely rise through the capillaries, and tend to form a hard crust in the paper so that the reagent cannot breakthrough to develop the test. Such saps can be examined if they are set to rise under a large glass cylinder or other cover. This procedure enables the measured quantity of sap to rise without forming a crust. As soon as absorption is complete the cover should be removed and the sap allowed to dry as usual. the reagent will rise later without difficulty. This procedure gives an insight into the form quality of the sap, but it tends to produce elongated shapes striving in almost parallel streams. Pictures of saps that rose under cover are not comparable with those that rose under normal circumstances. It is never advisable to set the reagent to rise under cover. this produces distended, gaseous looking forms.

PREPARATION OF THE REAGENT:

1 gr. of the metalsalt in question is dissolved in 99 ml of distilled water and called a 1% solution. Correspondingly 2 gr. in 98 ml water is called 2%. Solutions of 1 weight or 1 gr./100 ml water can of course be used. It is immaterial which method is used for the reagent in these test, but the chosen should be used constantly.

Conclusion:

Plant test are not influenced by the person making them. If the same experimental conditions are kept with exactitude, particulary as regards the plant, the parts used, the complete destruction before the extraction of the sap and so on, any number of people can work interchangeably on long series.