Further Notes on the Acquisition and Use of Photo-electric Cells

Since publishing the recent article (Shelford and Kunz '29) in this Journal, several cases of the purchase of untested and hence almost useless photo-electric cells by ecologists have come to the writer's attention. In addition, the form of the cells was wholly unsuited to ecological or other biological work. They were mounted for use in radio tube or similar sockets, and hence not easily insulated. To date, cell makers have apparently assumed little or no responsibility for the standardization of cells beyond a minimum suitable for physical laboratories, and have merely made them and sold them without regard to their fitness for the purpose for which they were purchased. The difficulty is in part due to the fact that the makers have little knowledge of the requirements of ecological work and ecologists have made no special demands. Makers construct apparatus suitable for use indoors, and with artificial lights, lenses, etc.