Davidson’s work

Plant specimens stored in an herbarium are pressed flat on paper sheets and dried. Other museum plant specimens are preserved in jars of alcohol. These spirit collections, also known as fluid-preserved or wet collections, preserve plants with fleshy flowers and fruit, which do not make good herbarium specimens. Plants stored in this way retain a more life-like three-dimensional appearance.

At Marischal College, researchers found that fluid specimens exposed to light began to turn brown after time, making them less useful for study. To combat this problem, researchers bleached plant specimens before storing them in the fluid. The ghostly white specimens retained their original structures for scientific study, but it became impossible to distinguish different plant tissues because they were now all the same colour.

Around 1895, Trail and Gage had begun searching for a method to retain the green colouring of museum specimens preserved in liquid. They devised a tedious method that required soaking the specimens in copper sub-acetate solutions for several months. This fixative prevented the normal cell degradation that takes place after a plant dies. They later soaked the specimens in alcohol for an additional month to extract any brown residue. Finally, they washed the specimens before mounting the plants in jars of preservative. This worked for some species, but not for others. The copper sub-acetate turned some plants black, a situation worse than the original problem.

Over the course of his own work, Davidson noted different results after varied preparations. In May 1907, he had one particular success when he used the same treatment with a different preparation on a Trillium grandiflorum. The bracts and sepals retained their natural green, while the petals remained white. Davidson had stumbled across an improvement to Trail and Gage’s method.

Through the summer and autumn of 1907, Davidson succeeded in preserving 160 genera (family subdivisions) never before preserved in their natural colour. He wrote an account for publication in a well-known monthly botanical paper to share the details of his process with “any others interested in this side of museum work.” While Davidson’s new procedure was not a revolution, he felt that people would appreciate something “more up-to-date than the old-fashioned white specimens” in “this advanced age of flying machines and Sub-marines.”

Davidson withdrew his account before publication, however, because he learned that Trail had already published an article on Davidson’s results. Trail’s article referred to Davidson as one who “had merely acted in a mechanical sort of way in carrying out some-one-elses [sic] experiments.” Davidson’s contribution received only a brief acknowledgement buried deep within the text.