CILIOPHORA, PROTOCILIATA 689 



Chen, T. T.: (1948) Chromosomes in Opalinidae with special refer- 

 ence to their behavior, morphology, etc. J. Morphol., 88:281. 



Fernandez, D. F.-G.: (1947) Observaciones cytologicas sobre las 

 Opalinas. Trab. Inst. Cien. Nat. Jose de Acosta, 1:352. 



Grasse, P.-P.: (1952) Traite de Zoologie. I. Fasc. 1. Paris. 



Hegner, R. W.: (1932) Observations and experiments on the opa- 

 linid ciliates of the green frog. J. Parasitol., 18:274. 



and Wu, H. F.: (1921) An analysis of the relation between 



growth and nuclear division in a parasitic infusorian, Oplaina 

 sp. Am. Nat., 55:335. 



Konsuloff, S.: (1922) Untersuchungen ueber Opalina Arch. 

 Protist 44:285. 



(1930) Haben die Opaliniden zwei Kernarten wie die anderen 



Infusorien? Ibid., 71:248. 



Metcalf, M. M.: (1909) Opalina. Arch. Protist., 13:195. 



— (1920) Upon an important method of studying problems of 



relationship and of geographical distribution. Proc. Nat. Acad. 

 Sc, 6:432. 



(1920a) The classification of the Opalinidae. Science, 52:135. 



(1923) The opalinid ciliate infusorians. Smithsonian Inst. 



U. S.Nat. Mus., Bull., 120:1 



(1928) The bell-toads and their opalinid parasites. Am. Nat., 



62:5. 



(1929) Parasites and the aid they given in problems of tax- 

 onomy, geographical distribution and paleogeography. Smith- 

 sonian Misc. Coll., 81: no. 8. 



(1940) Further studies on the opalinid ciliate infusorians and 



their hosts. Proc. U. S. Nat. Mus., 87:465. 

 ten Kate, C. G. B.: (1927) Ueber das Fibrillensystem der Ciliaten. 



Arch. Protist., 57:362. 

 van Overbeek de Meyer, G. A. W. : (1929) Beitrage zur Wach- 



stums- und Plasmadifferenzierungs-Erscheinungen an Opalina 



ranarum. Arch. Protist., 66:207. 

 Wetzel, A.: (1925) Vergleichend cytologische Untersuchungen an 



Ciliaten. Ibid., 51:209. 



