Invertebrates and Vertebrates Have Evolved Different Strategies to Change the Length/space

Essay

Invertebrates and vertebrates have evolved different strategies to change the length/space constant (λ) of a neuron. For each strategy, say whether this increases or decreases the length constant and what property in the following equation it influences. $\lambda = \sqrt { d R _ { m } / 4 R _ { i } }$ A. Invertebrates increased the diameter of the axon.
B. Vertebrates use myelination of the axon.