I. On the minute structure of the lung of the newt with especial reference to its nervous apparatus
The lungs of the newt and triton are essentially simple sacs without any septa projecting into their interior, so that they are remarkably well suited for microscopic examination. They are covered externally by a layer of endothelium, but there are no stomata to be found between the endothelial cells. Under this is a small quantity of areolar tissue containing a plexus of yellow elastic fibres, with the long axis of the meshes arranged in the long axis of the lung-sac. Under this is a layer of non-striped muscular fibres, which forms a complete investment for the lung. These muscular fibres are disposed circularly. They present the same structure as similar cells in the mesentery of the newt. Each cell contains an intra-nuclear and intracellular plexus of fibrils.