Plate 33. 



Artificially produced zonal spherulites of calcium carbonate. 



Fig. 1. Spherulite produced through the periodic precipitation of calcium car- 

 bonate by adding ammonium carbonate to sea water, X 350. 



2. Other spherulites produced similarly to spherulite represented by fig. 



1, X 700. 



3. Spherulites formed through bacterial action on calcium acetate in Great 



Salt Lake water, X 50. Preparation by K. F. Kellerman. 



4. Spherulites bacterially formed in Great Salt Lake water, X 100. Prepa- 



ration by K. F. Kellerman. 

 272 



