What are the balloon-like structures known as tyloses?

From where does the secondary meristem originate?

Aerating pores are present at places on the cork cambium. These are called

Read the different components from $(i)$ to $(iv)$ in the list given below and tell the correct order of the components with reference to their arrangement from outer side to inner side in a woody dicot stem.
$(i)$ Secondary cortex $(ii)$ Wood $(iii)$ Secondary phloem $(iv)$ Phellem
The correct order is:

In a stem which is covered by periderm and in which stomata are absent,gaseous exchange takes place through

In dicot stem,the secondary growth takes place by