i66 RESEARCH IN PROTOZOOLOGY 



and karyosomal chromatin and their changes under different con- 

 ditions of metaboHsm and in mitosis. In addition, the chromosome 

 number of all of the species should be completed, the chromosome 

 cycle more fully elaborated with the aid of the Fuelgen method, 

 and the critical value of the method itself should be verified for 

 the PROTOZOA generally. 



The morphology of the pseudopodia of the various species should 

 be subjected to comparative study under experimental control with 

 special reference to temperature, hydrogen-ion concentration, and 

 a possible metabolic cycle in connection with mitosis. 



The question as to races within the species based upon size as 

 indicated by Dobell and others of the English school, should be 

 subjected not only to statistical study by measurement, but to 

 refined morphological comparisons, to continued study of indi- 

 vidual cases of infection by a particular race over a period of time 

 under varying conditions of diet and also in culture under varying 

 conditions of media, temperature and hydrogen-ion concentration. 



From the standpoint of development there should be a con- 

 tinued statistical study of an infection in man and in some amen- 

 able culture mammal in which encystment occurs, such as Macaciis, 

 under constant conditions of diet to determine whether or not 

 there is any significant order in the fluctuations in number of the 

 parasites and whether or not there are any critical moments in 

 such cycles which might lead to the detection of, or to the increase 

 of an improbability of sexual reproduction. A comparable study 

 should also be made of the several species in culture, with a view 

 to finding out the cytological and physiological interpretation of 

 the fusions of active individuals which we have observed in Enda- 

 mwba gingivalis and in two other species. In the developmental 

 cycle both in feces and in cultures much remains to be done in 

 establishing a timed chronology of the changes in the cyst and 

 correlating this with the segregation and reduction of the glycogen 

 and the formation, aggregation, and disappearance of the chroma- 

 toidal bodies with relation to external and internal conditions. 



The possibility of a cycle within the bowel independent of dis- 

 charge in the feces and of a cycle in the tissues in the case of 

 Endamwba dysentcrice should be investigated. 



The faunistic aspects of the amoebae of the human digestive tract 

 are difficult of analysis, because of the movements of human popu- 

 lation, and the practical difficulties of securing comparable data 



