98 VEGETABLE CELLS. 



begun to decay, the contents (the mucilaginous layer with 

 the chlorophyll- and starch-globules) separate from the 

 wall and lie effused in the cavity of the cell. In this 

 case the new cells do not usually originate as small, 

 colourless, homogeneous globules of mucilage, but as 

 larger globules of the confluent cell-contents, composed 

 of mucilage, chlorophyll, and amylum. On the very 

 outside a layer of homogeneous mucilage is always de- 

 posited, and forms a sharply- defined surface. A distinct 

 membrane is quickly produced on this surface. The cell- 

 contents are so arranged within this that the chlorophyll- 

 and amylum-globules lie at the periphery, while the 

 middle part of the cavity is filled with transparent fluid. 

 These cells, whether they be formed within healthy or 

 decaying cells, originate through abnormal cell-formation, 

 and stand, apparently, in no necessary relation to propa- 

 gation ; therefore ordinarily they perish without further 

 development. In isolated cases, however, they behave 

 like germ-cells (spores), and are developed into new 

 plants. 



In Plate II, figs. 1 and 2 represent an old utricle of 

 Bryopsis Balbisiana, wherein abnormal cell -formation is 

 occurring. In fig 1, a and b, the cell-contents are dead 

 and beginning to dissolve. They consist of scattered chlo- 

 rophyll-globules and mucilage-granules. The parts 

 c and d, on the contrary, possess active living contents, 

 surrounded by a mucilaginous layer. They are connected 

 together by a mucilaginous cord : this cord is the rem- 

 nant of the mucilaginous layer which formerly coated the 

 part a. In an earlier stage it was thicker, and is now 

 gradually becoming thinner. Pig. 2 represents the same 

 portion of an utricle some time later; the connecting 

 cord of mucilage has disappeared, which has resulted 

 from its becoming gradually thinner, until it was torn 

 across, and united perfectly with the two living portions 

 of the cell-contents, c and d. The former, <?, is now a 

 defined, ellipsoid portion of contents, altogether free, and 

 coated over its whole surface with a thin layer of homo- 



