258 PROCEEDINGS OP THE 



zoid. When the antheridia are ripe the water must be swarming 

 with the antherozoids which are set free. The antheridia are an 

 orange colour, and are enclosed in a transparent envelope. When 

 the time comes for fertilisation the enveloping cells of the oogonium 

 separate at the top and leave an opening by which the anthero- 

 zoids enter, or sometimes the neck elongates, and they enter at 

 the side, just below the coronula. Large numbers of the fossilised 

 fruits of Charophytes are found in the secondary and tertiary 

 beds. The oogonium is preserved owing to its secretion of lime, 

 so that it becomes what is known as " lime shelled." This happens 

 only in the case of Chara ; Nitella does not secrete lime. The 

 cells of the coronula do not secrete lime, neither does the basal 

 cell ; there is, therefore, always an aperture at the base of the 

 fossil oogonium. The plant itself also secretes lime, but only on 

 the outside, while the fruit secretes it within its enveloping cells 

 so that the oospore becomes encased in a hard shell. Charo- 

 phytes never come to the surface of the water in which they grow. 

 They are to be found in pools, lakes, and especially fen ditches ; 

 recently dug-out clay-pits always contain them in two or three 

 years. They cannot stand against stronger vegetation, and the 

 secretion of lime may be an attempt to strengthen their weak 

 stems. The apparatus suitable for collecting charophytes is a 

 vasculum as airtight as possible, and plenty of newspaper or 

 old handkerchiefs, a drag, and a hoe, preferably having an 

 extension piece so that the handle may be lengthened. It is 

 always necessary to do a great deal of wading, and there is 

 nothing like the hand for getting specimens. If it is possible, 

 work down to the bottom and grasp the wiry root, then wash the 

 plant and wrap it in paper or cl oth. By this means good specimens 

 may be obtained, whereas it is almost impossible to obtain satis- 

 factory ones by grasping the branches. The plants will bear 

 no exposure to the air — after twenty-four hours' exposure little 

 remains but a crumbly heap of lime. When drying, very strong 

 pressure should be applied, so that the plant may be pressed into 

 the paper. The speaker had specimens one hundred years old 

 perfectly preserved in this way. The lecture was illustrated by 

 lantern slides, and micro-slides were exhibited under several 

 microscopes. 



Dr. J. R. Leeson drew attention to the reversed spiral of the 

 enveloping cells of some of the fossil specimens of oogonia : 



