FIXATION IMAGES OF SIEVE ELEMENT PLASTIDS IN BETA *

Abstract

429 from that of ain iplosed voltage very close to their owI frequeicy. is But these and other fragmentary indications point to quite different meanings for electroreceptor input in different species. Suniimiary.-Sternopygus displays (a) nonisynchronous, tonic "position" and (b) phasic "movement" units and (c) units which are synchronous (with electric organ discharge) aild tonic in response to objects near the fish. Some of the latter code by systematically shifting spike phase (latency) relative to the electric organ; this may be a new form of nerve impulse code. Some code by shifting the probability of firing but, strangely, without any phase shift. Patternls of runs and misses in the last group show a strong negative serial correlation for two or more intervals. Nonsynchronous units are not only uninfluenced by electric organ frequency but still respond to objects after electric organ silence. The remarkable variety of types of electroreceptors bespeaks differentiation of functions. Facilities for these experiments were kindly provided by the M\lutsetn CGoeldi, Brazil.