THE FUNDAMENTAL ORGANIZATION 



65 



one of the Myxosporidia) in which the centriole emerges from an 

 enveloping plastin-like matrix, which, like a nucleolus, then degen- 

 erates and disappears. 



3. Nuclei With Pole Plates and Without Endobasal Bodies. — This 

 type of nucleus is characterized by the entire absence of endobasal 

 bodies. A hyaline mass, which stains with difficulty, may, however, 

 be present at the spindle poles during nuclear division, but in 

 many cases it cannot be detected in the resting nucleus. During 

 division it occurs in characteristic forms known as pole plates. 



Fig. 33. — Bodo lacertae Grassi. Early stages of division of the basal bodies, (l/b); 

 blepharoplast ring (bl); nucleus and parabasal body (p). (After Belaf.) 



In the micronuclei of Paramecium caudatum such a mass forms a 

 hyaline cap at one pole of the otherwise chromatin-filled resting 

 nucleus. Observations are entirely lacking in regard to division 

 of this mass during reproduction, but similar aggregates of non- 

 staining substance are present at the distal ends of the daughter 

 nuclei during stages of division (Fig. 35). Similar pole plates appear 

 as broad, flat and hyaline ends of the spindles of Actinosphaerium 

 eichhornii according to Hertwig (1898), in the spindle of Tricho- 

 syhaeri urn sieboldi according to Schaudinn (1899), or in the macro- 

 5 



