In plain words
The totality of Sūkṣma-śarīras is Samaṣṭi when it is the object of one Buddhi, like a forest or reservoir, and Vyaṣṭi when it is the object of many Buddhis, like trees or portions of water.
The totality of Sūkṣma-śarīras is Samaṣṭi when it is the object of one Buddhi, like a forest or reservoir, and Vyaṣṭi when it is the object of many Buddhis, like trees or portions of water.