EXTENSIONS 377 



previous pattern. A cortical pattern of polarized, anisotropic 

 lateral striping is always visibly present no matter how we fragment 

 the cell. The location, number, length and direction of asymmetry 

 of the oral primordium are determined by the pattern of the ecto- 

 plasm, quite independently of the location or quantity of the nucleus 

 and endoplasm. Induction of mouthparts at the terminus of the 

 anlage is also to be correlated with the polar ectoplasm, for in 

 heteropolar implants two sets of mouthparts are produced in 

 correspondence with two separate posterior poles although the 

 endoplasms would mingle indiscriminately and the nuclear nodes 

 may be located anywhere. Even the smallest, nucleated pieces bear 

 short lengths of a few lateral ciHary bands which are separated at 

 graded distances by granular stripes so that healing produces a 

 locus of stripe-width contrast and regeneration of a whole is always 

 guided by this preexisting polarity and anisotropy. Even in the 

 relatively dedifferentiated cyst stage, striping and polarity are 

 evident, according to the drawings of Stein; and in other ciUates 

 which have been carefully studied all landmarks do not disappear 

 and some cortical pattern evidently persists (e.g., Garnjobst, 1937). 

 Empirically, Stentor possesses at all times — in all our experi- 

 mental situations save one: denudation of the ectoplasm — an 

 obviously persistent visible pattern. However the basic cortical 

 pattern may be conceived, to postulate it as axiomatic or as a factor 

 always present from the initial state in any experiment we can 

 perform, has an important consequence. This is that we need not 

 and cannot derive the final form and pattern from molecules and 

 their spontaneous aggregation or interactions as such. True, these 

 cortical cell patterns would have arisen at some time in the early 

 evolution of life, and phenomena such as the association of collogen 

 into fibrous sheets may give us some hint of how this could have 

 been brought about. Once developed, the relatively large scale 

 patterns we have in mind, like such replicating units as macro- 

 molecules, chromosomes, and perhaps kinetosomes, could have 

 been carefully conserved and never destroyed but passed on by 

 genetic continuity, pattern producing further pattern, and these 

 patterns gradually evolving in complexity, on the one hand into 

 very complicated unicellular flagellates and ciliates and on the 

 other into equally complex yet cryptic egg patterns capable of 

 guiding the development of the whole range of elaborate multi- 



