Page:An introduction to physiological and systematical botany (1st edition).djvu/67

 Rh Mirbel supposes to produce the liber or young bark, and at the same time, by a peculiar arrangement of the vascular parts, the alburnum or new wood. His opinion is strengthened by the observation of a tribe of plants to be explained hereafter, Palms, Grasses, &c. in which there is no real bark, and in which he finds that the woody fibres do actually produce the cambium. Dr. Hope's experiment will scarcely invalidate this opinion, because it may be said the cambium had already in that case formed the liber.

This matter will be better understood when we come to speak of Mr. Knight's experiments on the course of the sap.