Development, and Structure of the Vegetable Cell. 125 



which are directed towards the extremities of the mother cell ; 

 between these and the septum produced by the mutually opposed 

 membranes of their primary cells a system of mucilaginous 

 filaments makes its appearance in the direction of their radii, 

 indicating the formation in them of secretion-cells similar to those 

 of the mother cell. These cells may be brought into sight by 

 the action of dilute solution of tannin and of some other 

 endosmotic fluids. 



Upon the different directions of growth of the two daughter 

 cells (i. e. whether they extend themselves more in the first or 

 the second of the indicated directions) depends both the greater or 

 less removal of the nuclei of the daughter cells from the median 

 line of the mother cell at the ap{K:arance of the septum, and also 

 the modifications in the mode in which this septum becomes 

 visible at the surface of the joint-cell. 



If the daughter cells at first follow especially the first indi- 

 cated direction of growth, i. e. if they increase most in breadth, 

 their central flattened walls attain the surface of the joint-cell, 

 whilsttheir free peripheral portions directed towards the extre- 

 mities of the mother cell scarcely form a hemispherical surface. 

 These mutually flattened walls appear, on coming into contact 

 with the wall oi the mother cell, as the new septum. 



The membranes of the secondary cell of the joint-cell, ft* ftlio 

 the chlorophyll-sac applied to their inner surface, cover the 

 outer circumference of the septum, and even conceal it when 

 a starch-vesicle or an opake chlorophyll-vesicle lies immediately 

 upon it. 



If, however, the daughter cells extend at first less in this 

 direction than in the direction of their length, so that their free 

 surface, instead of becoming hemispherical, approaches more or 

 less to a spherical form, those phenomena occur which have 

 hitherto been usually observed and described as the normal 

 process. 



In this state (in which the small secretion-vesicles surround- 

 ing the cell-nucleus are in process of absorption, and therefore 

 collapse readily by any diosmotic process) the secondary [cell, 

 with the adherent chlorophyll-sacs, readily sinks down upon the 

 more or less spherical daughter cells, which, however, always 

 have a part of their surface flattened against each other, forming 

 the depression which is frequently observed and regarded as a 

 preliminai-y of the septum-formation. 



That this fold-like depression is not essentially connected 

 with the formation of the septum, but that it occurs only in a 

 less complete and not perfectly regular course of development, 

 appears from the circumstance that it is met with chiefly in cul- 

 tivated plants, or in those which have grown in their natural 



