86 H. M. WOODCOCK. 



D. mincliinii the encystmeiit process is more typical, and 

 tliere is a well-marked ectocyst. 



The nuclear changes at the commencement of spornlation 

 in D. irregularis are very important. The karyosome 

 becomes divided up in the nucleoplasm, and with successive 

 divisions of the sporont-nucleus the resulting fragments 

 (daughter-karyosomes) become apportioned out among the 

 daughter-nuclei. The karyosomatic fragments break down 

 still further, and ultimately become incorporated with the 

 chromatin of the nucleoplasm. I do not believe any nuclear 

 material is, at this period, eliminated. 



(7) My observations tend to prove that the earliest nuclear 

 divisions are completely amitotic. The mnltijilying nuclei 

 become distinguishable into two kinds, germinal ones, which 

 subsequently form the sporoblast-nuclei, and large somatic 

 or sterile ones, which eventually become dissipated in the 

 surrounding cytoplasm. This pi'ocess represents the nuclear 

 purification of D. irregularis. The germinal nuclei divide 

 by mitosis, and the attraction-spheres have very large and 

 apparent centrosomes. These attraction-spheres can also 

 exist and divide independently, and are to be met with scat- 

 tered about in the cytoplasm. Some appear to come into 

 relation with the large sterile nuclei, and probably help to 

 bring al)Out their disintegration. 



(8) In both D. irregularis and D. minchinii, and 

 especially in the latter, the process of sporoblast-formation 

 is characterised by the remarkable extent to which the inter- 

 twining of the lobes and processes of the two associates is 

 carried. As a result of this practically all the cytoplasm is 

 utilised to form the gametes. There is no cystal residue 

 C'gregarinoid soma'') left over. The primary sporoblasts 

 or gametes are quite simple and all alike morphologically, 

 and conjugation is, therefore, completely isogamous. I have 

 never observed the least movement in live cysts at this 

 period, and do not believe the so-called " danse des sporo- 

 blasts " occurs. 



(9) Spore- and sporozoite-formation in D. irregularis 



