N1665 robert hooke, an english scientist, published his book micrographia, in which he described that pieces of cork viewed under the microscope presented small cavities similar to pores which were filled with air. based on later knowledge, of what were the walls of those cavities constituted? what is the historical significance of his observatio

The walls observed were plant cell walls, that form the tissue.

Explanation:

Hooke's observation resulted in the discovery of the plant cells, which only began possible when the microscope was invented. As a result, Hooke defined the term "cell" to describe the "cavities" visible under the microscope.  

answer:

convection currents in the magma drive plate tectonics. heat generated from the radioactive decay of elements deep in the interior of the earth creates magma (molten rock) in the aesthenosphere. the aesthenosphere (70 ~ 250 km) is part of the mantle, the middle sphere of the earth that extends to 2900 km.