DISCOVERY OF SUGAR ON DOUGLAS FIR 



85 



ed to it and feed upon it. The principal regions where 

 Professor Davidson's investigations show the sugar to be 

 produced are in the hottest and dryest parts of the in- 

 terior of British Columbia, between the 50th and 51st 

 parallels, and between 121 and 122 longitude. These 

 areas take in the Thompson River Valley, west of the 

 mouth of the Nicola River, the district near the junction 

 of the Fraser and Thompson Rivers at Lytton, and a 

 small part of the Fraser Valley, above Lillooett. In the 

 Kamloops district, ihe Nicola and Similkameen Valleys 

 and the eastern part of the State of Washington it is 

 also reported to occur. 



On first viewing the phenomenon, Professor Davidson 

 was inclined to think the sugar resulted from punctures 

 made in the leaves by insects, probably aphides, as he 

 knew the Tamarix mannifera yielded a mucilage-like 

 sugar when attacked by the Coccus as a result of which 

 came the manna of Mt. Sinai. However, this idea was 

 quickly dispelled when he found only healthy Douglas 

 fir yielded a sugar harvest, ones practically free of any 

 insect life. Thus the phenomenon was evidently the 

 result of natural causes, turning the investigator's atten- 

 tion to an examination of hours of sunlight, amount of 

 moisture usually existing and similar things. This re- 

 sulted in the finding that in the above mentioned dis- 

 tricts of the dry-belt on gentle slopes facing east and 

 north in comparatively open areas where the fir trees 

 got plenty of exposure to sun, the sugar producing trees 

 chiefly grew. Where the firs stand densely, or where the 

 trees are on fully exposed southern and western slopes 

 the sugar is not generally found, as the ground in this 

 latter area dries out very quickly. From this it was evi- 

 dent that moisture played an important part in the sugar's 

 production when combined with certain requisites of 

 sunlight. Where a great many leaves are exposed to the 

 sun, as in the case of the firs standing on comparatively 

 open areas on the slopes facing east and north, an abund- 

 ant formation of carbohydrates occur in a day. In the 

 ordinary course of nature's working these carbohydrates " 

 would be carried to the growing tissues or storage ones, 

 which is the case on Douglas fir in heavily forested areas. 

 But throughout the dry-belt region the trees receive a 

 much greater amount of sunlight over a greater number 

 of hours per day than in other localities where they 

 grow. Here, in the dry-belt, the ground and atmosphere 

 are also warmer, the air circulates more freely than in 

 the coastal regions where the dense fir forests stand. 

 Thus in the dry-belt where the firs are subjected to a 

 long succession of unclouded days of blazing sunlight in 

 summer, and where the soil condition provided warmth 

 and moisture, the trees gather a great deal more car- 

 bohydrates than normally. The soil's increasing warmth 

 over so great a period of sunlight permits the roots to 

 maintain or increase activity and continue noctumally. 

 This increased root pressure, and cessation of transpira- 

 tion, causes the leaves to become water-gorged. This 

 water contains a sugar created by the reconversion of 

 starch into sugar. But the warm, dry atmosphere exist- 

 ing even through the night in these dry-belt regions, 



quickly evaporates the water, and the sugar remains to 

 form drops of various sizes deposited at the leaf tips, 

 some of which so large they fall onto branches and 

 foliage below, resulting at times in irregular deposits as. 

 shown in the photograph. 



By reason of the necessity for a succession of sunshiny 

 days to produce the sugar, the Douglas fir of course 

 does not yield a harvest that could annually be depended 

 upon. For, a couple of wet days, or a few cloudy ones 

 are sufficient to disarrange those atmospheric conditions 

 which make the sugar possible. A cloudy day would 

 permit the tree to utilize in the regular way much of the 

 excess sugar and to horde the remaining portion as a 

 future food reserve. A day or more marked by a drop 

 in temperature would check the labor of the sugar-form- 

 ing cells in the leaves, and the diminishing of the soil's 

 heat lessen the root activity, causing a diminishing in 

 the exudation of the water and a lowering of the root 

 pressure. Similarly a day of rain would still more lower 

 the soil temperature as well as that of the atmosphere. 

 For these reasons the sugar cannot be depended upon to 

 yield an annual harvest. This the Indians knew, and in 

 good years stored up as much of the delicacy as was 

 obtainable. The following analysis, made by Dr. F. T. 

 Shutt, Dominion Chemist, Ottawa, Canada, and by the 

 Bureau of Chemistry Washington, D. C, where there is 

 a laboratory specially equipped for the examination of 

 saccharine substances, are of great interest by the high 

 degree of constancy of composition the fir sugar, or 

 manna, showed. It is still more interesting owing to 

 the finding that it contains a large percentage of an ex- 

 tremely rare variety of sugar; indeed, this particular 

 variety is more abundant in the product of the Douglas 

 fir than any other known plant. It was formerly ob- 

 tained from a shrub in Turkestan and Persia. Of this 

 pure and rare trisaccharide the Douglas fir sugar contains 

 almost fifty per cent. Thus, while the fir sugar will 

 never play a part as a food supply, like the product of 

 the cane and beet, it will likely eventually prove valuable 

 for use in chemistry, and perhaps in other ways which 

 the scientific experimenting conducted by those interested 

 in the discovery will bring to light. And in the heart of 

 British Columbia the Indians will still gather it as they 

 did before the white man came. Unique as the dis- 

 covery is, it is further remarkable that so long a time 

 elapsed before it attracted scientific attention as related 

 herein. Perhaps the Indians intentionally held the fact a 

 secret. 



Of this Douglas fir manna, as it is called, the weekly 

 bulletin of the Forest Service, District No. 1, at Missoula, 

 Montana, says : "An interesting phenomenon which few 

 of us have probably observed is the occurrence of 'fir- 

 sugar' or Douglas fir manna, which is occasionally form- 

 ed during summer droughts, or in dry-belt regions on 

 the leaves and twigs of the Douglas fir. 



"According to information from published records 

 which have been furnished by Dr. Weir, the manna is 

 not the result of the activities of insects, but is a natural 

 exudation from the tips of the needles. The manna is 



