18 Transactions of the Society. 



seems to be much the more important, for in this instance varia- 

 tions arise under conditions which appear to be perfectly uniform. 

 Some of the principal forms are shown in the accompanying 

 sketch,* drawn with the camera lucida ; the smaller figures are 

 magnified about 300 diameters, and represent the earlier forms of 

 development towards the centre of the cell ; the larger and darker 

 are magnified 500 times, and are those which have developed more 

 recently, near the groove, with a more abundant supply of air. 

 The cultivation is now two months old, and the cell is nearly filled 

 with organisms : the nutrient fluid must be almost exhausted. 



* To be seen iu the Library. 



