In considering “cork” for the purpose of ascertaining its characteristics, texture and composition we will, instead of analyzing the material after it has reached the market, look at it from the standpoint of botany and learn of its formation upon the tree, from which it is procured. It appears that the word “cork”[21] in botany signifies a growth peculiar to all plants and pertaining to none in particular, being described as “a peculiar tissue in the higher plants forming the division of the bark (which name is sometimes restricted to the dead tissues lying outside the cork); consisting of closely packed air-cells nearly impervious to air and water and protects the underlying tissues.”[22] Again, “It is produced by the activity and division of certain merismatic cells known as phellogen or cork cambium which are situated immediately within the epidermal covering of the young growth. As the cork cells grow older, their protoplasmic contents disappear and are replaced by air. In order that this formation may be clearly understood, I will quote from a paragraph entitled “Cork and Epidermal Formations Produced by It” contained in “A Text Book on Botany,” by Sacks. [21] See “Etymology of Word” in preceding chapter. [22] “New English Dictionary,” Murray. “When succulent organs of the higher plants, no longer in the bud condition, are injured, the wound generally becomes closed up by cork tissue, i.e., new cells arise near the wounded surface by repeated division of those which are yet sound, and these forming a firm skin separate the inner tissue from the outer injured layers of cells. The walls of this tissue offer the strongest resistance to the most various agencies, similar to the cuticular layers of the epidermis in their physical behavior, flexible and elastic, permeable only with difficulty by air and water, they for the most part soon lose their contents and become filled with air. They are arranged in rows lying at right angles to the surface or parallelopipedal form, and form a close tissue without intercellular spaces. These are the general distinguishing features of cork tissue. It is formed not only on wounded surfaces, but arises in much greater mass where succulent organs require an effectual protection (e.g., potato tubers) or where the epidermis is unable to keep up with the increase of circumference where growth in thickness continues for a long period. In these cases the cork tissue is formed even before the destruction of the epidermis, and when this splits under the action of the weather and falls off, the new envelope formed by the cork is already present. The cork tissue is the result of repeated bipartitions of the cells by partition walls, rarely in the epidermis cells themselves, more often in the subjacent tissue. The partition walls lie parallel to the surface of the organ, divisions also taking place in a vertical direction, by which the number of the rows of cells is increased.