stant fraction of the amount of energy which the sense organ has received previously.

VIII

Repeated stimulation of the kind just described, has frequently been called a process of adaptation to a stimulus. As such it has been used as a criterion for the presence of a "higher behavior" in many animals. Similarly, the fact that the reaction time continues to increase steadily has been taken to indicate a process of learning.

The experiments forming the basis of this. communication, have, however, shown that these phenomena are dependent on changes which take place within the sense organs themselves. In addition, they have demonstrated that the process of "adaptation" to a photic stimulus in Ciona is subject to the course of a chemical reaction. The reverse of this reaction determines the ability of the organism to become "dark adapted." Furthermore, the changes which occur in the reaction time during both of these adaptional processes are consistent with the principle underlying the Weber-Fechner rule. This requires that in order to act as a stimulus, the light must form a quantity of a substance such that it will bear a definite ratio to the amount of that substance already present in the sense organ. The matter of "higher behavior" is nowhere evident in these experiments. SELIG HECHT

PHYSIOLOGICAL LABORATORY,
CREIGHTON COLLEGE OF MEDICINE,
OMAHA, NEBR.

A METHOD FOR PREPARING PECTIN

PECTIN bodies is a term applied to a group of substances occurring in practically all plants and fruits. They are complex carbohydrates, probably derived from one mother substance known as pectose, and are closely allied to the plant gums and mucilages. Pectin occurs most abundantly in the apple, quince, currant and gooseberry and appears in small quantities in strawberries, raspberries, etc. In suitable amounts of sugar and acid the pectins have the property of gelatinizing fruit juices or hot-water extracts of fruit pulp in which

they are present or to which they may be added. The reason why some kinds of fruit juices do not jelly is due to an insufficient amount of pectin being present in them. For example the practise of mixing apple juice with raspberry or strawberry juice is for the purpose of increasing the pectin content and thereby make jelly from juices where it would be impossible to do so otherwise. The juices from the various kinds of fruits are known for their distinctive flavors. These qualities are impaired when a combination of juices are blended together. For this reason it has been the aim of manufacturers to make highgrade jellies from the low-containing pectin fruit juices by adding to them the purified pectin. The pectin, as now prepared, is very expensive and therefore its use in jelly-making is very limited.

Pectin is slightly soluble in water and therefore the pulp or pomace resulting from the pressing of ripe fruit contains practically all of the pectin. Hot water will slowly extract the pectin and for this reason fruits are cooked to a pulp with water before extracting the juice for jelly-making.

In the fruit-producing sections of the state of Washington, there is a considerable amount of cheap material such as cull apples, pomace from cider presses and cores and peelings from canning establishments which go to waste. This waste material might be utilized for the preparation of pectin which, in turn, could be used in making jelly from those fruit juices which lack pectin. The object of the experiment carried on in this laboratory was the finding of some simple and inexpensive process for the preparation of pectin from these waste products, without the use of alcohol, as is the case in Goldthwaite's1 method.

The principle of the method is based upon the fact that pectin as extracted from the pulp or pomace is in a colloidal state and can be readily changed by electrolytes. Since pectin, after precipitation, must be dispersed again in order to be of any value as a gelatinizing agent, an electrolyte that will produce a reversible precipitation must be chosen. Also 1 J. Ind. and Eng. Chem., 2 (1910), 457.

the electrolyte chosen must be non-poisonous. Lead acetate or basic lead acetate will precipitate pectin, but the precipitation is an irreversible one, and the amount of lead absorbed or combined may be poisonous. For these reasons ammonium sulfate was chosen. Bigelow, Gore and Howard2 in their review of the literature on pectin mention that in 1898 Bourquellot & Herissey used ammonium sulfate as a precipitant for pectin obtained from gentian root. Other than this no further use has been made of this precipitant for pectin.

METHOD

60 grams of dried apple pomace were boiled three successive times with 200 c.c. of water, filtering after each boiling. To each of the 100 c.c. of filtrate 25 grams of ammonium sulfate were added3 and then heated to 70° C., whereupon the pectin was precipitated as a grayish white flocculent precipitate. The precipitate was separated from the mother liquor by filtering. (The mother liquor can be evaporated and the residue used again or the residue can be used as a fertilizer.) The precipitate was dissolved in hot water and again precipitated with ammonium sulfate. Again it was filtered and the precipitate was removed from filter paper and dried at 60-70° C. and when dry was washed several times with cold water to remove adhering ammonium sulfate. The precipitate was dried again and its gelatinizing power was tested by adding to a 1 per cent. solution of the pectin 0.5 per cent. solution of citric acid and 65 gm. of sugar. This solution was boiled for 10-20 minutes and upon cooling a nice stiff jelly was produced. The taste did not indicate the presence of ammonium sulfate and upon dissolving the jelly in hot water only a slight milkiness was produced when tested for sulfates.

In order to determine whether the yield of 2 Bul. 94 U. S. Dept. Agr. Bur. Chem.

3 If wet pomace is used it will require a somewhat larger amount of ammonium sulfate. First add 25 grams per 100 c.c. and if precipitation does not occur, add successive portions of 5 grams until precipitation occurs. The pectin may also be precipitated by saturating the solution in the cold with ammonium sulfate.

pectin by the above method was equal to the yield produced by the alcohol precipitation method, two samples of apple pomace from the same lot were treated exactly alike, except that ammonium sulfate was used in one case and alcohol in the other as the precipitating medium. The pectin was dissolved and reprecipitated in each case, then filtered and the precipitate was removed from filter paper and dried. The ammonium sulfate was removed from the one by washing with cold water, again dried and weighed. The amount of pectin recovered by each method is recorded in table below.

of the Great Lakes. Thus far, however, moss suitable for surgical dressings has not been reported in any large quantities from this region. The excessive heat in summer and the extreme frost in winter creates a condition that is uncongenial for desirable species to grow and thrive.

On the Pacific coast, extending from Oregon to Alaska, large numbers of sphagnum bogs occur. It is estimated that in Washington alone there are 25,000 acres of cranberry marsh. Of course a large proportion of this area does not have usable moss. Most of the bogs in Washington that are close to the Pacific Ocean are "raised bogs," that is, the center is higher than the margin, often a foot or more. Consequently, surrounding each of these is a marginal ditch filled with water. Raised bogs also occur along the northern Atlantic, especially in Nova Scotia and Newfoundland. This type of bog occurs only where there is an excessive amount of moisture and thus most congenial for the growth of sphagnum. Moreover, it is this kind of bog that usually contains the species most suitable for surgical dressings. Hence the most promising fields for the location of suitable surgical moss may be expected along the northern Atlantic and Pacific coasts.

USES OF SPHAGNUM

Sphagnum is frequently called "peat moss," because it, with other plants growing in undrained bogs, eventually make peat, which is used extensively for fuel in some countries. Sphagnum is very commonly used by nurserymen and others for packing; especially is it desirable about the roots of plants when moisture is required for a considerable length of time. A number of varieties of orchids thrive as well in sphagnum as in their native haunts. This moss makes an excellent insulator, much better than sawdust or even cork, but of course it can not be used where it is exposed to moisture. It excels sawdust as a medium for packing and shipping raw fruits, like grapes, because when one bunch goes bad" the moss immediately absorbs the moisture and prevents the infection spreading.

In Sweden some of the coarser kinds of paper, like wall-paper, wrapping paper and building paper, are made from this moss. It is used in Alaska and other places where it is abundant to bind up wounds of domestic animals, particularly when there is some discharge. In such cases the moss is applied directly to the wound. When it is dried it is often used as bedding for horses and other animals. This moss has also been used in Scotland and Ireland as a home remedy for absorbing the discharge from boils and other suppurating wounds. The American Indians made use of dried sphagnum for diapers for their babies. In Alaska they still do it. The Alaska Indians also make a very wholesome salve, used for cuts, by mixing sphagnum leaves with tallow or other grease and working the two well together.

It is known that in Germany a fairly good cloth is made by mixing sphagnum with wool and weaving them together. Promising results have also been obtained when it is used as a fertilizer. Not that it adds much plant food to the soil, but that it acts as a stimulant

by holding a large quantity of water. It is of particular value when applied to the roots of trees along parking strips in cities.

Dr. Walton Haydon, of Marshfield, Oregon, used sphagnum extensively while in the service of the Hudson Bay Company at Moose Factory during the years 1878-1884. After the moss was collected and sorted it was sprinkled with a weak solution of carbolic acid. When nearly dry it was stored in a jar with a tight cover until used. In using it a thin cotton dressing was laid on the wound or sore, then a layer of moss and the whole dressing wrapped with a bandage. Dr. Haydon found it best to keep the sphagnum with a small amount of antiseptic moisture in it, as it breaks up and becomes dusty when thoroughly dried.

Sphagnum was used or at least recommended for use during both the Napoleonic and Franco-Prussian wars, and was employed to a limited extent in the Russo-Japanese war. It was not, however, until the present world

war broke out that it became extensively employed as a modern surgical dressing.

Shortly after the war was declared in 1914, Dr. C. W. Cathcart, an Edinburgh surgeon and a lieutenant-colonel in the medical corps of the British army, began experimenting with sphagnum in one of the Scottish hospitals. The first published account of these experiments, together with the general account of the moss as a surgical dressing, appeared in the Scotsman of November, 1914.2 Dr. Cathcart then formed an organization for collecting and preparing the peat moss for surgical pads in Edinburgh. This was the first organization formed for this purpose among the allied nations. In September, 1915, a second one was established in the south of Ireland by the Marchioness of Waterford. The work thus begun was so promising that new organizations sprang up all over Scotland and Ireland under the War Dressing Supply Organization in Edinburgh, and the Irish War Hospital Supply Depot in Dublin. During this experimental stage there was considerable opposition to this kind of surgical pad, but as time went on and the method of making the dressings was improved, this opposition disappeared and in February, 1916, the British War Office accepted them as "official" dressings. With this recognition and organization the work rapidly increased, so that during the summer of 1918 the sphagnum pads produced by Great Britain are numbered in the millions per month, Scotland alone being asked to supply 4,000,000 sphagnum dressings a month.

In America the sphagnum work on a large scale, has been more recent. During the summer of 1916, Dr. J. B. Porter, of McGill University, became interested in peat moss for surgical dressings.3 Samples were collected in eastern Canada, especially in Nova Scotia, and sent to Britain for approval. It was late in the season before definite reports could be ob2 Charles W. Cathcart and I. Bayley Balfour, "Bog Moss for Surgical Dressings," The Scotsman, No. 17, 1914.

3 John B. Porter, "Sphagnum Surgical Dressings," International Journal of Surgery, May, 1917.

tained from these samples, so little was done before the bogs were frozen.

In the spring and summer of 1917 this work was continued by the Canadian Red Cross under the direction of Dr. Porter. Although no very large number of dressings was made, yet the organization was extended and perfected, and the bogs containing the desirable moss located, so that if the demand became more urgent the production of this kind of dressing could be readily pushed. This demand came in January, 1918, in the form of an order from the British War Office, for 20,000,000 sphagnum surgical dressings. The Canadian Red Cross is thus doing extensive work along this line during 1918.

After the United States entered the war more interest was taken in this work by Americans but it was not until March 1, 1918, that sphagnum was officially recognized by the National Red Cross of America. At that time a preliminary order for 50,000 pads was given to the Seattle Chapter and these have been made on the campus of the University of Washington under the direction of the writer.

The faculty of the University of Washington, feeling the importance of this phase of War Emergency work and wishing to assist in completing as rapidly as possible this large allotment of pads, voted to require all women of the first and second years of the university to register for two hours a week for moss work during the spring quarter. The request for this work came originally from the women themselves through the dean of women. They felt that since the men were required to devote eight hours a week to military drill without university credit, the women also should do some definite war work under university supervision.

COLLECTING AND SORTING

Before beginning the collection of sphagnum one should know exactly what is needed. There are over forty species of this moss in America of which only four (S. imbricatum, S. palustre, S. papillosum and S. magillanicum) are at present used for surgical dress