does not alter our results because in order to be able to close our discrete master equation, we neglect disintegration of a nuclei via the *end evaporation and addition* pathway. Our approximation of irreversible nucleus formation has been employed in the past by several researchers and the results have been quantitatively compared with the experimental data on protein polymerisation, justifying our approximation. [@tuomas_science; @hong; @tuomas_review]

Before we delve deeper into our analysis, a few remarks should be made. In principle, we consider four mechanisms that are responsible for the time evolution of the length distribution: the *primary nucleation*, the *end evaporation and addition*, the *body evaporation and addition* and the *scission and recombination* pathway. Our goal in this work is very specific and is to compare the *early time* kinetics of the two pathways of interest, which are the *end evaporation and addition* and the *body evaporation and addition*. However, if we do not include the *scission and recombination* pathway, the resulting dynamical equations will be singular, meaning that we can make a parameter corresponding to this pathway small but never put it to zero. Hence, it is for purely mathematical reasons that we make use of the most general 