338 GARY N. CALKINS 



Onychodromus grandis (Maupas), Stylonychia pustulata (Mau- 

 pas, Prowazek, '99), each having two micronuclei; in Didinium 

 nasutum, with two or three (Prandtl, '06), in Blepharisma undu- 

 lans, with from four to five micronuclei (Calkins, '12) and in 

 Bursaria truncatella with from sixteen to eighteen micronuclei 

 (Prowazek, '99). 



Maupas ('88) described an anomalous, additional, or prelim- 

 inary division in the case of Euplotes patella and in E. charon, 

 where it is found in both conjugants. In other cases where such 

 a division occurs (in the peritrichida) it is limited to the mi- 

 crogamete (Vorticella monilata, V. nebulifera (Maupas, '88), 

 Carchesium polypinum (Maupas, '88; Popoff, '08), Ophrydium 

 versatile (Kaltenbach, '15), and Opercularia coarctata (En- 

 riques, '07). 



The prophases of the first maturation spindle in ciliates are fre- 

 quently highly characteristic. In Loxophyllum meleagris (Mau- 

 pas, '88), Spirostomum teres (Maupas, '88), Euplotes patella 

 (Maupas, '88), Colpidium colpoda (Hoyer, '99), and in Ble- 

 pharisma undulans (Calkins, '12) however, there appe^s to be 

 no typical prophase stages beyond the swelling of the nucleus, 

 fragmentation of the homogeneous chromatin of the micronu- 

 cleus and formation of the chromosomes. Hoyer ('99) describes 

 a typical spireme in the case of Colpidium colpoda, but this is 

 very exceptional in ciliates and needs confirmation. 



In Paramecium (aurelia, bursaria, and caudatum) a very typi- 

 cal prophase stage occurs in the form of a crescent, derived from 

 the homogeneous micronucleus which first draws out in the form, 

 of a long cylinder which later forms the characteristic crescent. 

 A modification of the crescent occurs in Chilodon uncinatus 

 (Maupas, '88; Enriques, '08), where the chromatin is drawn out 

 in the form of an elongate comma-shaped band. This is still 

 further modified in Cryptochilum-nigricans (Maupas, '88), Vorti- 

 cella monilata and V. nebulifera (Maupas, '88), and in Oper- 

 cularia coarctata (Enriques, '07), where a long chromatin rod 

 extends, in some cases, the entire length of the cell. 



Still another type of prophase, and a type to which Uroleptus 

 belongs, is found in Onychodromus grandis (Maupas, '88), Bur- 

 saria truncatella (Prowazek, '99), Didinium nasutum (Prandtl, 



