ORIGINS OF AGAMIC PATTERNS 615 



and apparently have no attached stage. They show a physiological and 

 morphological dorsiventrality with ventral ciliary bands in elliptical pat- 

 tern, except for slight lateral asymmetry. These forms undergo trans- 

 verse fission like most ciliates. 



At present we have only the data of observation concerning these pat- 

 terns of suctorial development. The peculiar development of axiate larval 

 patterns from internal buds, with progress of differentiation from one side 

 to the other, differs from anything known in other groups. The pole of 

 attachment is physiologically ventral in some forms (Fig. ig2,A), physio- 

 logically apical in others (Fig. 192, C), and physiologically almost anterior 

 in still others (Fig. 192, D). 



CERTAIN FEATURES OF PATTERN IN OTHER AXIATE PROTOZOA 



Axiate patterns of individual cells composing the spherical colonial 

 flagellates, such as Pandorina, Volvox, and various others, appear to be 

 directly related to a surface-interior difference; but they may represent 

 polarities persisting through the successive divisions from the primary 

 cell of the colony, the divisions being parallel to the polar axes of the cells. 

 A relation between cell formation and pattern, apparently similar to that 

 so general among Sporozoa, appears in certain reproductions of Masti- 

 gophora. Swarm-spore development in Nodiluca is preceded by repeated 

 nuclear division near the surface of a part of the parent body, the apical 

 region. Following this period, budding of a cell body in relation to each 

 nucleus results in development of a swarm spore or perhaps a gamete with 

 flagella originating from the apex of the bud (Pratje, 192 1). The surface- 

 interior differential of the mother cell evidently plays a part in deter- 

 mining the position of the nuclei and may be concerned, together with 

 the budding, in determining the axiate pattern of the spore. The longi- 

 tudinal fission so generally characteristic of Mastigophora may be re- 

 garded as a sort of budding of the two cells from each other, with polarity 

 persisting but with reconstitution of symmetry or asymmetry in each 

 part in definite relation to the polar pattern as separation proceeds. The 

 transverse fissions characteristic of most ciliates involve, of course, polar 

 reconstitution. In many ciliates, however, extensive dedifferentiation of 

 the pre-existing pattern is associated with fission, so that what finally 

 results is actually a new pattern, but one that develops in direct relation 

 to the original pattern and presumably under its influence. For exar^ple, 

 the two new cirrus fields appearing in fissions, as well as in reconstitutions, 



