i6o 



RELICS OF PRIMEVAL LIFE 



ing canals. In Eozoon the canals form ramifying 

 groups in the middle planes of the laminae, and 

 proceed at first almost horizontally, dividing into 

 smaller branches, which ultimately give off brushes 

 of minute tubuli running nearly at right angles to the 

 surfaces of the lamina, and forming the extremely 

 fine tubulation which Dr. Carpenter regarded as 



J^o o <^ o ci 



w C>^ o C> "^ O 



t> o o o ^ 



O r> o r\ O 



Fig. 39. — Cross section of J/iinute Tubulin about 5 microms. in 

 diameter {magnified). 



the proper wall (Figs. 38, 39). In my earlier de- 

 scription I did not distinguish this from the canal- 

 system, with which its tubuli are inwardly con- 

 tinuous. Dr. Carpenter, however, understood this 

 arrangement, and has represented it in his figures ^ 

 (see also Fig. 28). It is evident that in a struc- 

 ture like this a transverse or oblique section will 

 show truncated portions of the larger tubes appar- 



* "Ann. and Mag. Nat. Hist.," ser. 4, xiii., p. 456, figs. 3, 4. 



