76 



THE MICROSCOPE AND ITS REVELATIONS. 



like those of the cyclical type of OMculina (Plate xv., g. 6). When a 

 vertical section is made through such a disk, it is found that these oblong 

 chambers constitute two superficial layers, between which are interposed 

 columnar chambers of a rounded form; and these last are connected to- 



Fio. 318. 



FIG. 319. 



Disk of Orbitolites tenuissimus, formed round fragment of previous disk. 



gether by a complex series of passages, the arrangement of which will be 

 best understood from the examination of a part of the sarcode-body that 

 occupies them (Fig. 319). For the oblong superficial chambers are occu- 

 pied by sub-segments of sarcode, c c, d d y 

 lying side by side, so as to form part of an 

 annulus, but each of them disconnected 

 from its neighbors, and communicating 

 only by a double footstalk with the two 

 annular ' stolons/ a a', I Z>' which obvious- 

 ly correspond with the single stolon of 

 ' simple ' type (Fig. 317). These indirect- 

 ly connect together not merely all the 

 superficial chamberlets of each zone, but 

 also the columnar sub-segments of the 

 intermediate layer; for these columns (e 

 e, e' e') terminate above and below in the 

 annular stolons, sometimes passing direct- 

 ly from one to the other, but sometimes 

 going out of their direct course to coalesce 

 with another column. The columns of 

 the successive zones (two sets of which are 

 shown in the figure) communicate with 

 Portion of Animal of Complex type each other by threads of sarcode, in such 



or Orbitohtes complanatus: a a', o o', ,- *, / ,-1 , , \ , 



the upper and lower rings of two con- a manner that (as in the simple type) each 



trie 



centric zones; c c, the upper layer of 

 superficial sub-segments, and d d, the 

 lower layer, connected with the annular 

 bands of both zones; e e and e' e', ver- 

 tical sub-segments of the two zones. 



column is thus brought into connection 

 with two columns of the zone next inte- 

 rior, to which it alternates in position. 



