Pollen Analysis Circular maintain contact with one another and maintain publication lists that had, until then, been published by Gunnar Erdtman as "Literature on Pollen Statistics and Related Topics". The first issue of the "Pollen Analysis Circular" was dated May 5, 1943 and published by Paul B. Sears (Oberlin College). Subsequent issues were generally edited by Sears, sometimes in cooperation with L.R. Wilson. In January 1945, the "Pollen Analysis Circular" was renamed the "Pollen and Spore Circular" to more accurately reflect its scope. After 1954, the Circular was incorporated into the "Micropaleontologist", soon renamed "Micropaleontology", published by the American Museum of Natural History.
Enteric coating However, as the solvents for such solutions are organic solvents, there's a concern about the toxicity potential of the traces of the residual solvents in the tablet coating. The first form of gastro-resistant coating was introduced by Unna in 1884 in the form of keratin-coated pills, although it was later discovered that they weren't able to withstand gastric digestion. Salol was also used by Ceppi as one of the first forms of enteric coating. However, the first material that was extensively used as enteric coating agent was shellac, since its introduction in 1930. Properly treated or hydrolyzed shellac showed different