562 JOHNSON. 



EXPLANATION OF PLATE XXVL 



Stentor cceruleus : conjugation, teratology, nutrition, defecation, and nierotomy. 



Fig. 49. To show line of junction of a conjugated pair. The suture is a dense, 

 refractive plane passing through the whole surface of contact. Zeiss, ~ . 



Fig. 50. A conjugated pair of very unequal size. Zeiss, |- ^ X 90. 



Fig. 51. Two separated nodes of meganucleus of conjugated specimen, sur- 

 rounded and connected by a reticulum of cytoplasm. In situ, from living speci- 

 men. Zeiss, ^ . 



Fig. 52. A conjugated pair in Stage H of Maupas. The fragmented mega- 

 nucleus yet retains its normal stainability. A new meganucleus {mgn}) is develop- 

 ing in each gamete. In the lower gamete two of the micronuclei are undergoing 

 atrophy within vacuoles. Composite of four transverse sections, 5/x thick. Cor- 

 rosive sublimate, picro-carmine, xylol balsam. Zeiss, | = X 240. 



Figs. 53-59 all studied with Zeiss' Hom. immers., 2 mm. and magnified 1400 ' 

 diameters. 



Figs. 53, 54. Two micronuclear spindles of different form from same gamete, 

 at " monaster " stage. Corrosive sublimate, picro-carmine, xylol balsam. 



Fig. 55. Micronucleus in its normal or resting state. Corrosive sublimate, 

 Czokor's alum cochineal, balsam. 



Fig. 56. Micronucleus enlarged at time of conjugation (Stage H, same prep, as 

 Fig. 52). 



Figs. 57, 58. Two stages in enlargement of anlage of new meganucleus. Un. 

 stainable. Example in Fig. 58 is accompanied by a micronucleus. Corrosive 

 sublimate, balsam. 



Fig. 59. Micronucleus within a digestive vacuole. Unstainable. Corrosive 

 sublimate ; Czokor's alum cochineal. 



Fig. 60. Node of meganucleus, from an ex-conjugate. (Same gamete as Fig. 

 57.) Stainability much reduced. Two vesicles of clear karyoplasm under nuclear 

 membrane. Zeiss, Homog. immers., 2 mm. comp. oc. 4 = X 950. 



Figs. 61 A-E. Stages in the formation of a double monster, and its return to 

 the normal condition. All drawn from living animal. Fig. 61 B (dorsal aspect) 

 three hours later than 61 A (ventral aspect). Fig. 61 C (ventral) drawn six hours 

 later than 61A. Zeiss, |. Fig. 61 D drawn fifteen hours later than 61 C. Zeiss, f. 

 Fig. 61 E represents the specimen thirteen hours later than 61 D. Zeiss, j'g-. 



Fig. 62. A Stentor feeding upon carmine grains, dorsal aspect. Arrows show 

 the direction taken by the carmine-particles. The stripes are omitted for sake of 

 clearness. Zeiss, y\ . From Ufe. 



Fig. 63. A specimen of S. ceBruleus that has fed upon minute green algae 

 (Scenedesmus). Defecation taking place at two different points simultaneously, 

 and a few minutes later at the normal place of defecation {a). From life. 

 Zeiss, j'j. 



' Figs. 64 A and B. Posterior merozoon of S. cceruleus ; A, dorsal, B, ventral 

 aspect ; regenerating adoral zone and mouth. A contractile vacuole present, and 

 meganucleus in condensed state (nign.). From life. Zeiss, ■^-^. 



