Assimilation is one of the types of interactions. Like accommodation it is also a form of social adjustment. But it is more permanent than accommodation. If person-to-person, person-to-group, or group to-group relations were to remain at the level of accommodation only, there would not have been any fusion of groups and their cultures.
Assimilation is possible only when individuals and groups are tolerant towards the cultural differences of others. Tolerance helps people to come together, to develop contacts towards to participate in common social and cultural activities.
Assimilation is possible only when the groups and individuals are in continuous contact with others. Hence isolation is a negation of assimilation. Not only physical isolation but even mental isolation retards assimilation.
Nitrogen is the most essential element for living being next to water. It constitutes 78% of earth atmosphere and present at about 10-15% in living protoplasm. These are present in form of proteins, vitamins, chlorophylls, cytochromes, nucleic acid, hormones and functional group of enzymes in plant cell.