jSo 



E. A. ANDREWS. 



there is a mass of coagulum that binds them all together to some 

 extent. 



The material binding the cases together, seen as a film in 

 Figs. 4 and 5, is so tenuous and transparent as to easily escape 

 notice, but when the aggregates form on the surface of the water 

 it is this common basis that enables one to pick up the aggregates 

 as one mass and when the leaves of Elodea die and macerate, it is 

 easy to obtain innumerable aggregates falling off but each firmly 

 bound into one unit by the film that underlies all the cases. 



FIG. 6. View from above of a small group of twelve formed on surface of 

 water. Camera lucida X 55. 



Even such a loose aggregate as that in Fig. 6, formed on the 

 surface of water is really bound into one mass that may hold 

 together through all the processes necessary for section cutting, 

 though in face view the film is not seen. This last figure well 

 illustrates the tendency of the FolUculina to build tubes in a 

 radiating group and to fill in most of the intervals in an irregular 

 way. 



