422 



THE FORMS OF CELLS 



[CH. 



of the first. There is a very neat expanded orifice in the cyst of 

 Chromulina (Fig. 136); it is doubtless fashioned in just as simple 

 a way, but how I know not. 



Passing from the sohtary flask-shaped cell of Lagena, but without 

 leaving the Foraminifera, we find in Nodosaria, Rheophax or Sagrina 

 constricted cyUnders, or successive unduloids, such as are repre- 

 sented in Fig. 137. In some of these, as in the arenaceous genus 



Fig. 136. Flask-shaped shells or cysts, a, b, Chromulina and 

 Deropyxis (Flagellata); c, Difflugia. 



tig. llil . Various species of Nodosaria, Rheophax. Sagrina. After Brady. 



Rheophax, we have to do with the ordinary phenomenon of a 

 partially segmenting cylinder. But in others, the structure is not 

 developed out of a continuous protoplasmic cyhnder, but, as we 

 can see by examining the interior of the shell, it has been formed 

 in successive stages, beginning with a simple unduloid ''Lagena,'' 

 about which, after it solidified, another drop of protoplasm accu- 

 mulated, and in turn assumed the unduloid or lagenoid form. The 

 chains of interconnected bubbles which Morey and Draper made many 

 years ago of melted resin are a similar if not identical phenomenon*. 



* See Sillijnan's Journal, ii, p. 179, 1820; and cf. Plateau, op. cit. ii, pp. 134, 461. 



