: an embryonic movement that involves streaming of material from the dorsal and lateral surfaces of the gastrula toward the blastopore and concurrent shifting of lateral materials toward the middorsal line and that is a process fundamental to the establishment of the germ layers
: independent development of similar characters (as of body structure in whales and fishes) by animals or plants of different groups that is often associated with similarity of habits or environment
: movement of the two eyes so coordinated that the images of a single point fall on corresponding points of the two retinas
: overlapping synaptic innervation of a single cell by more than one nerve fiber—compare divergence 2
Mathematical property of infinite series, integrals on unbounded regions, and certain sequences of numbers. An infinite series is convergent if the sum of its terms is finite. The series + + + + + ... sums to 1 and thus is convergent. The harmonic series 1 + + + + + ... does not converge. An integral calculated over an interval of infinite width, called an improper integral, describes a region that is unbounded in at least one direction. If such an integral converges, the unbounded region it describes has finite area. A sequence of numbers converges to a particular number when the difference between successive terms becomes arbitrarily small. The sequence 0.9, 0.99, 0.999, etc., converges to 1.