1056 PARASITES OF PROTOZOA 



described by Dangeard (1895) in a host he considered to be Amoeba 

 verrucosa, invades the nucleolus, in which it appears at first as a vacuole 

 enclosing a granule — the former its cytoplasm, the latter its nucleus. 

 Growth of the parasite is rapid (Mattes, 1924), and as it proceeds 

 the chromatin is used up. The stainable nuclear material becomes re- 

 stricted to the periphery in a reticulated structure (as noted by the writer 

 in Niicleophaga of devescovinid flagellates), or to the central zone (Fig. 

 218C, D), as in hyperparasitized Endamoeba disparata (Kirby, 1927). 

 Eventually the nuclear material disappears, and the interior is entirely 

 occupied by the parasite. 



The parasitized nucleus hypertrophies considerably (cf. Fig. 218F 

 and J; O and N), up to several times its original diameter. The para- 

 site must obtain material for its continued growth by diffusion from the 

 cytoplasm through the nuclear membrane. Though Mercier (1910) men- 

 tioned considerable hypertrophy of the nucleus of E. blattae, he showed 

 spores in nuclei in which there seems to have been little enlarge- 

 ment. This is unlike the usual situation. Perhaps the very thick membrane 

 of the nucleus of E. blattae has an influence in restraining the growth 

 of the parasite. Lavier (1935b) noted precocious spore formation in 

 Nucleophaga of Entamoeba ranarum, but stated that it generally occurs 

 when the parasite has attained a large size. In Nucleophaga of devesco- 

 vinid flagellates, notably that in Caduceia theobromae, expansion of the 

 nucleus cannot occur equally in all directions, because of its relation- 

 ship to the axostyle. Instead, it is pushed out on one side, and often has 

 a bilobed figure (Fig. 218K, L). This figure sometimes is retained 

 in the mature sporangium; often it fills out. As has been noted also of 

 Sphaerita, the size of the mature sporangium, as well as the number of 

 spores, is subject to considerable variation in the same species of Nu- 

 cleophaga. 



It has been stated that spore formation is in certain forms continuous, 

 and that there may be present in an individual at a given time mature 

 spores and granules corresponding to spores not yet formed (Lavier, 

 1935b). It is more general, however, for the spores to be formed 

 simultaneously, the entire thallus being converted into the group. Other 

 granules, which have been seen by the writer among the spores, prob- 

 ably represent residual or discarded material; there is no evidence for 

 maturation of later spores. 



