In the classic conception of many authors, the pore or duct becomes visible by enzymatic dissolution in an adult wall, having acquired its defini­ tive thickness and melanization. However, such a phenomenon is difficult to follow in the living fungus and it is not generally possible to determine whether the characteristic structure of the pore is formed before, during, or after conidiogenesis. Moreover, in this conception, the porospores should be enteroblastic, whereas studies to date under electron micro­ scope show that they are holoblastic, as seen earlier (chapter III).