A historical note on the iodine-sulphuric acid reaction of amyloid.

The historical development of the iodine-sulphuric acid reaction for amyloid is described. The reaction dates back to 1814 when Colin and Gaultier de Claubry, and independently Stromeyer, introduced the iodine reaction for starch. A variant of the acidified iodine reaction appears to have been used for printing paper by Gmelin in 1829, and in 1838 Schleiden used the iodine-sulphuric acid test on plants to demonstrate what he considered to be a transformation of the plant material into starch. Shortly afterwards Payen (1839) defined "cellulose", and the iodine-sulphuric acid reaction became a standard procedure used by botanists to demonstrate this plant component. In 1853 Virchow used Harting's (1847) procedure to demonstrate the reaction of Purkynĕ's corpora amylacea to this test, on the assumption that they might be cellulose derivatives, and applied it to what appeared to be similar corpuscles in a "waxy" spleen. The first histochemical reaction for amyloidosis had thus been introduced into pathology, and continued to exert from that time on an important influence on amyloid research, whose impact is felt to the present day.