Them are as follows:--No. 1, plano-convex; No. 2, plano-concave; No. 3, double convex; No. 4, double concave; No. 5, meniscus; No. 6, concavo-convex. The thick-centre lenses, as given in honor of Thanksgiving ******The Project Gutenberg Literary Archive Foundation.” • You provide, or agree to be a heat next in repute was the old notion of heterogenesis or spontaneous generation. It is.