THE OCEANIC TINTINNOINA OF THE PLANKTON GATHERED DURING THE 



LAST CRUISE OF THE CARNEGIE 



INTRODUCTION 



The Tintinnoina are one of the major subdivisions of 

 the ciHate protozoans. The group is among the more 

 complex of these ciUates, ranking in structural elaboration 

 with the symbiotic ciliates of ruminant mammals and 

 the peritrichous ciliates. 



The body is conical or trumpet-shaped, and attached 

 by the inverted apex to an external lorica, which is not in 

 close contact with the animal as in the Sarcodina and 

 Mastigophora. The broad basal end of the body projects 

 out of the lorica through the oral opening of the latter 

 and is provided with a crown of highly differentiated 

 motor organs. These are relatively few in number (12 to 

 24) and of complicated structure. This wreath or circlet 

 of membraneiles is composed of separate blades, the 

 whole forming a left-twisted spiral, one end of which 

 enters a preoral cavity on one side of the depressed 

 frontal area, in the middle of which arises a piston 

 organelle. Each blade is made up of a line of 8 adjacent 

 lamellae, each consisting of a dense rodlet and a thin, 

 wide, hyaline sheet. In cross section the lamella is sickle- 

 shaped and presents the following structures: (a) an en- 

 closing pellicular envelope, (b) a ground substance in 

 which are embedded 6 fibrils in the blunted outer and 

 denser part, and a single one in the hyaline material on 

 the convex side of the lamella. In the blunt end are vari- 

 cosed alveoles strung along an irregular line. Basal 

 granules connect this system of fibrils, and these in turn 

 are in contact with the neuromotorium. On the inner 

 face of each blade is a lappet organ. 



The neuromotorium is a granular spinille-shaped or 

 even round body lying between the body wall of the ani- 

 mal and the gullet, which latter is below the preoral de- 

 pression, antl into which extends a brush of cilia. The 

 neuromotorium is the dynamic center of the animal. It 

 serves as the center of coordination in locomotion and 

 other body activity, and at the time of binary fission be- 

 comes the directing agent for the forming of the lorica. 

 From the neurotnotorium arise several fibers, the most 

 important of which connects with the membraneiles. 

 Others probably connect the body cilia and the ciliary 

 membrane when this last structure is present. 



The ciliary membrane is present in Tinttnnidiiim , Tin- 

 tinnopsis, Codonella, Stenosemella, Codonellopsis, and 

 probably other genera. It is made up of a line of strong, 

 long cilia which extend down the body on the ventral 

 (gullet) side. Body cilia are mainly confined to the 



upper three-tenths of the body. They are sparse and often 

 rather long. Some are used as stays by the animal when 

 extended from the lorica. Small patches of cilia are often 

 found in rows below the peristome, on the body. 



The animal has i to 100 macronuclei, the number 

 being usually a pair, and S to 20 being common in 

 eupelagic species; the number is constant save during 

 reproductive periods. The macronuclei are large and 

 sausage-shaped. The micronuclei are small and globular. 

 They lie near the macronuclei and are usually similar in 

 number to the latter. 



During reproduction by binary fission, a chromophile 

 cloud of granules is accumulated in the body in the 

 region of the gullet. This material is prominent at about 

 the time the cytoplasmic organs appear. As progressive 

 nuclear and cytoplasmic changes occur, these granules 

 come to form a shieldlike mass above the frontal area of 

 the forming posterior schizont. That this material forms 

 the substance of the lorica is evident from the following 

 considerations: {a) its structure is alveolar, {b) its con- 

 sistency resembles that of the lorica, {c) it makes its 

 appearance at the time of fission and at no other time, 

 {d) it occurs in all species examined, {e) it forms in a 

 position such that it may be discharged by existing 

 organs, probably the mouth, and the discharged material 

 is whipped about by the membraneiles. These data fit in 

 well with observations on tintinnids which have been 

 watched in the living state at the time of fission. In 

 short, the lorica is the product of secretion and behavior. 



The lorica is usually cuplike, with a single large open- 

 ing. The morphological characters of diagnostic value 

 are: the finer structure of the wall, which may be laminar, 

 prismatic, alveolar, or hyaline; the inclusions and the 

 tendency to incorporate adherent detritus; the propor- 

 tions, which are generally pretty constant; the suboral 

 and circumoral dilTerentiations, including the nature of 

 the margin, the collar, teeth, bands, rings, and ledges, and 

 the interpolated collars or other structures; the general 

 proportions of the bowl, its outline, and the extent and 

 level of its maximum diameter; the aboral structures, 

 such as the pedicel, knob, lance, apophyses, skirt, and 

 other significant differentiations, and the form and pro- 

 portions of the aboral opening when present; the differ- 

 entiations of the surface of the lorica, such as rings, 

 angles, ribs, ridges, plications, shelves, and flutings, to- 

 gether with the number, spacing, distribution, direction, 



