596 MB. S. LE M. MOOEE S STUDIES 



tissue are not peuetrated by threads*, which are also absent from 

 the proximal wall of the layer bounding the chamber in which 

 the embryo lies ; except for this they may be traced with ease 

 throughout the endosperm. 



Had Tangl worked with the seeds of StrycJinos Ignatialae would 

 have found the examination of the threads a much easier task ; 

 to see them it is sufficient to place sections of the hard dark 

 endosperm in water — a cell from the central mass of the endo- 

 sperm so treated is shown at figure 1. The area of thickening is 

 much swollen, and in the case represented shows a couple of 

 strongly marked striae close to each other and to the primary 

 wall, but this is by no means the only method of striation ; some- 

 times the outer half only of the swollen areaf is marked with a 

 number of fine, closely-placed lines, or it may be uniformly so 

 marked throughout. The lumen of the cell is polyhedral in out- 

 line, with convex sides and acute angles, the latter usually point- 

 ing towards the corners of the cell ; its granular protoplasm 

 contains oily globules. The threads can easily be seen with a 

 5-inch objective, but higher powers are necessary for their satis- 

 factory examination, which shows them to be, except for their 

 larger size, similar to the threads of S. Nux-vomica ; there is the 

 same grouping, the same outward bulging of the flank-threads, 

 the same inequality in calibre, and the same continuity through 

 the primary wall with the threads of neighbouring cells. 



Many of the threads of cells treated with water alone appear 

 to stop short at the primary wall, but if sections be placed for a 

 few minutes in a solution of iodine in alcohol, to which is added 

 a small quantity of water, the nature of the intercellular commu- 

 nication is brought more clearly into view (fig. 2). The primary 

 wall can now be distinguished only aa a fine bright line traversed 

 by the stained threads, the course of many of which, not being 

 in the same plane as that of the section, appears to be inter- 

 rupted ; the protoplasm within the angular lumina is more deeply 

 stained than that of the threads ; it is invested by the more 

 lightly stained limiting layer (represented by the dark outline of 

 the cell-contents shown in figs. 4 & 17). Great difference exists 



* In ordinary circumstances, for in sections placed for twenty-four hours in 

 chloriodide of zinc continuity can be traced right up to the epidermis. 



t By "swollen area" I do not mean the primary wall, which itself swells up 

 somewhat in water. Cf. figs. 1 & 2. 



