Text 1391
The lord instructs Šrila Runa Gosvāmī
319
trimšal-lakşāni pašavaḥ catur-laksāni mānuşāh
“There are 900,000 species living in the water. There are also 2,000,000 nonmoving living entities ( sthāvara ) such as trees and plants. There are also 1,100,000 species of insects and reptiles, and there are 1,000,000 species of birds. As far as quadrupeds are concerned there are 3,000,000 varieties, and there are 400,000 human species.” Some of these species may exist on one planet and not on another, but in any case within all the planets of the universe—and even in the sun—there are living entities. This is the verdict of Vedic literatures. As  Bhagavad-gītā  (2.20) confirms:
na jāyate mriyate vā kadācin  
 nāyaṁ bhūtvā bhavitā vā na bhūyaḥ  
 ajo nityaḥ śāśvato 'yaṁ purāṇo  
 na hanyate hanyamāne śarīre
“For the soul there is never birth nor death. Nor, having once been, does he ever cease to be. He is unborn, eternal, ever-existing, undying and primeval. He is not slain when the body is slain.”
Since the living entities are never annihilated, they simply transmigrate from one life form to another. Thus there is an evolution of forms according to the degree of developed consciousness. One experiences different degrees of consciousness in different forms. A dog's consciousness is different from a man's. Even within a species we find that a father's consciousness is different from his son's and that a child's consciousness is different from a youth's. Just as we find different forms, we find different states of consciousness. When we see different states of consciousness, we may take it for granted that the bodies are different. In other words, different types of bodies depend on different states of consciousness. This is also confirmed in  Bhagavad-gītā  (8.6):  yaṁ yaṁ vāpi smaran bhāvam . One's consciousness at the time of death determines a type of body of the living entity. This is the process of transmigration of the soul. A variety of bodies is already there; we change from one body to another in terms of our consciousness.
TEXT 1399
কেশান্দ্রি-শতেক-ভাগ পুনঃ শতাংশ করি ।।
তার সম সূক্ষ্ম জীবের ‘স্বরূপ’ বিচারি ॥ ১৩৯ ॥
keśāgra-śateka-bhāga punaḥ śatāṁśa kari tāra sama sūkṣma jīvera ‘svarūpa’ vicāri