380 [Proc. B.N.F.C, 



27 January. 



The President, Lavens M. Ewart, in the chair. F. J. Bigger, 

 honorary secretary, read a paper on " The Discovery of a 

 Souterrain at Stranocum," in the demesne of W. Ford- 

 Hutchinson, which was illustrated by a number of excellent 

 drawings and sections made by W. J. Fennell, and by numerous 

 photos taken by Alex. Tate. This souterrain has already been 

 described in the Ulster Journal of Archceology for April, 1897, 

 so that it is unnecessary to repeat the description. After some 

 remarks by F. W. Lockwood, J. Cunningham, Alex. Wilson, 

 John M. Dickson, and others, the president called upon Dr. W. 

 Donnan to read a communication on "Fresh-Water Algae." 

 Dr. Donnan began by showing the ease with which the study 

 of these lowly forms of life may be carried on, as every pool or 

 sheet of standing water teems with them. He then briefly 

 described their position in the vegetable world, coming among 

 the thallophytes, there being no distinction between leaf and 

 stem. They are distinguished from the fungi (the other large 

 group of thallophytes) by possessing chlorophyll, the green 

 colouring matter which gives to plants their power of digesting 

 mineral substances. They are cellular plants, with cell walls of 

 cellulose, of which also paper is made ; many of these cell walls 

 exhibit the most beautiful forms, and the effect is often increased 

 by the arrangement of the chlorophyll grains in strings and 

 spirals through the cells. Dr. Donnan then described some of 

 the more familiar and beautiful of the fresh-water algae, such as 

 the Pleuracoccus, which forms a green scum on standing water. 

 The "red snow" and "gory dew" are forms of algae with red- 

 dened chlorophyll. They usually multiply by simple division 

 into two halves, each of which goes and does likewise, ad infinitum, 

 but it sometimes happens that zoospores are formed by the 

 breaking up of the protoplasmic chlorophyll. Each zoospore 

 has two ciliae, by which it can swim about until they are ready 

 to settle down as members of the ordinary community of 

 protacocci. Closely allied forms are the desmids and the 



