THE OPALINID CIIJATE IXFUSOEIANS. 



69 



slender than P. macrocaudata^ and its nuclei are more elongated than 

 those of either the latter species or P. onentalis. It resembles P. 

 regnlaris (next to be described), but its nuclei, though elongated, 

 are not yet in a definite anaphase stage, such as is found in the latter 

 species. Its nuclei are more elongated and more pointed than those 

 of P. rhinoderinatos. Evidently the species is distinct. 



Fig. 40. — Protoopalina adstralis : a and b, individdals with nuclei in active mitosis 



PREPARATORY TO FISSION, NDCLEAE STRUCTURE NOT SHOWN IN DETAIL, X 1,000 DIAME- 

 TERS ; C AND d, ORDINARY INDIVIDUALS, X 460 DIAMETERS. 



The material, which has lain for 80 years in the rectum of the 

 host, preserved in alcohol, is in good condition for general study, but 

 the nuclear phenomena are not as clear as we would wish. The 

 elongated, usually pointed nuclei are in a phase of mitosis approach- 

 ing the equatorial plate stage. They are thus less advanced in 



