406 Prof. H. Mohl on the Structure of Dotted Vessels. 



exhibits merely a still further development of the forms hi- 

 therto considered. 



EXPLANATION OF THE PLATES. 

 The fractions under the figures show the degree in which they are mag- 

 nified. 



Plate VIL 



Fig. 1 . Cassyta glabella. The lateral wall of a dotted tube abutting oh 

 another vessel. 



Fig. 2. Cassyta glabella. Vertical section through the walls of two 

 dotted vessels applied to one another, a. Cavity between two dots ; b. ca- 

 nal of dot. 



Fig. 3. Cassyta glabella. The transverse dissepiment of a dotted vessel 

 pierced by a round aperture. 



Fig. 4. Dot more highly magnified. 



Fig. 5. Laurus Sassafras. Portion of a dotted vessel. The canals of the 

 dots are widened on the inner side in the form of long fissures. 



Fig. 6. Aleurites triloba. Wall of a dotted vessel which is contiguous to 

 another vessel. 



Fig. 7. Aleurites triloba. Wall of a dotted vessel which is contiguous to 

 a cell. The canals of the dots are so strongly widened within, that the dots 

 appear to be surrounded by a border. 



Fig. 8. Aleurites triloba. A dot from fig. 6. more highly magnified. 



Fig. 9. Laurus nobilis. Transverse section through the walls of two con- 

 tiguous dotted vessels. Funnel-shaped widening of the canals of the dots 

 toward the inner surface of the vessel. 



Fig. 10. Elceagnus acuminata. Portion of a dotted vessel ; fissure- like 

 form of the canals of the dots. 



Fig. 11. A dot of the same more highly magnified. 



Fig. 12. Bombax pentandrum. Wall of a dotted vessel which borders 

 on a second vessel. 



Fig. 13. Bombax pentandrum. Wall of a dotted vessel contiguous to a 

 cell. The canal of the dots is widened within. 



Plate VIIL 



Fig. 1. Chilianthus arboreus. Wall of a dotted tube contiguous to a cell. 



Fig. 2. Chilianthus arboreus. Wall of a dotted tube contiguous to an- 

 other vessel. The dots are very much widened, so as to make the vessel 

 appear like a scalary tube. 



Fig. 3. Chilianthus arboreus. Vertical section through the walls of two 

 contiguous vessels. 



Fig. 4. Clematis Vitalba. Dotted vessel, a. Portion of the same unin- 

 jured ; b. portion with the outer coat of the walls of the vessel removed by 

 an oblique section, so that the fissure-like form of the inner aperture of the 

 canals of the dots may be more clearly seen. 



Fig. 5. Reticulate vessel of Cactus brasiliensis. The canals of the dots 

 at a have an oblique direction, in consequence of which the lines which in- 

 dicate the outer and inner aperture cross one another. 



Fig. 6. Tilia parvifolia. Wall of a dotted tube contiguous to a second 

 vessel. 



Fig. 7. Daphne Mezereum. Large dotted tube. 



Fig. 8. Daphne Mezereum. Small dotted tube, which is merely marked 

 by threads without any dots. 



