The second project is on the lack of coexistence in a three species two seasons resource competition model. Investigating how temporal variation in environment affects species coexistence has been of longstanding interest. The competitive exclusion principle states that $n$ niches can support at most $n$ species, but what constitutes a niche is not always clear. For example, Hutchinson in 1961 drew attention to the diversity of phytoplankton coexisting despite the small number of resources in ocean water. Hutchinson then suggested that this could be explained by a changing environment; times when different species are favored would be considered different niches. In this paper, we examine a model where three species interact with each other solely through the consumption of one resource. The growth per resource rates, death rates, resource rates, and methods of resource consumption vary periodically through time. We give a necessary and sufficient condition for the coexistence of all three species. In particular, this condition rules out coexistence for the mean field limit of a three species two seasons model studied by Chan, Durrett, and Lanchier in 2009.