Srimad Bhagavatam Canto 11, Chapter 03, Text 39

SB 11.3.39

andesu pesisu tarusv aviniscitesu
prano hi jivam upadhavati tatra tatra
sanne yad indriya-gane ’hami ca prasupte
kuta-stha asayam rte tad-anusmrtir nah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
The spirit soul is born in many different species of life within the material world. Some species are born from eggs, others from embryos, others from the seeds of plants and trees, and others from perspiration. But in all species of life the prana, or vital air, remains unchanging and follows the spirit soul from one body to another. Similarly, the spirit soul is eternally the same despite its material condition of life. We have practical experience of this. When we are absorbed in deep sleep without dreaming, the material senses become inactive, and even the mind and false ego are merged into a dormant condition. But although the senses, mind and false ego are inactive, one remembers upon waking that he, the soul, was peacefully sleeping.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
When a living entity is awake the material senses and mind are constantly active. Similarly, when one is sleeping the false ego recollects one’s waking experiences, and thus one experiences dreams or fragments of dreams while sleeping. But in the state of prasupti, or deep sleep, both the mind and the senses become inactive, and the false ego does not recall previous experiences or desires. The subtle mind and false ego are called linga-sarira, or the subtle material body. This linga-sarira is experienced in the form of temporary material designations such as “I am a rich man,” “I am a strong man,” “I am black,” “I am white,” “I am American,” “I am Chinese.” The sum total of one’s illusory conceptions of oneself is called ahankara, or false ego. And due to this illusory conception of life the living entity transmigrates from one species of life to another, as clearly explained in Bhagavad-gita. The spirit soul, however, does not change its constitutional position of eternity, knowledge and bliss, although the soul may temporarily forget this position. To cite an analogous situation, if one dreams at night that he is walking in the forest, such a dream does not change one’s actual position of lying in bed within his apartment. Thus it is stated in this verse, kuta-stha asayam rte: despite the transformations of the subtle body, the spirit soul does not change. Srila Sridhara Svami has given the following example to illustrate this point. Etavantam kalam sukham aham asvapsam, na kiñcid avedisam. One often thinks, “I was sleeping very peacefully, although I was not dreaming or aware of anything.” It can be logically understood that one cannot remember something of which he has had no experience. Therefore, since one remembers peacefully sleeping although there was no mental or sensual experience, such a memory should be understood to be a vague experience of the spirit soul.
Srila Madhvacarya has explained that the demigods, who are a superior race of humanlike entities on the higher planetary systems of this universe, do not actually undergo the gross ignorance of deep sleep as do ordinary human beings. Because the demigods have superior intelligence, they are not merged into ignorance at the time of sleeping. In Bhagavad-gita Lord Krsna says, mattah smrtir jñanam apohanam ca. Sleep is apohanam, or forgetfulness. Sometimes by dreaming there is smrti, or memory of one’s actual condition, although in a dream one may experience one’s family or friends in an altered, illusory state. But all such conditions of remembering and forgetting are due to the presence of the Supersoul within the heart. By the mercy of the Supersoul one can have a preliminary glimpse of the soul by remembering how one was peacefully resting even without mental or sensual experience.
According to the authorized commentaries on this verse, aviniscitesu means sveda-jesu, or born from perspiration. Srila Madhvacarya has pointed out, bhu-svedena hi prayo jayante: the earth’s dew is to be considered the perspiration of the earth, and various species of life are generated from dew.
In the Mundaka Upanisad (3.1.9) the situation of the soul in relation to prana is explained:
eso ’nur atma cetasa veditavyo
yasmin pranah pañcadha samvivesa
pranais cittam sarvam otamm prajanam
yasmin visuddhe vibhavaty esa atma
“The soul is atomic in size and can be perceived by perfect intelligence. This atomic soul is floating in the five kinds of air [prana, apana, vyana, samana and udana]. The soul is situated within the heart, and it spreads its influence all over the body of the embodied living entities. When the soul is purified from the contamination of the five kinds of material air, its spiritual influence is exhibited.” Thus in the innumerable species of life the spiritual soul remains situated within prana, or the material life air.
Srimad Bhagavatam Canto 11, Chapter 03, Text 38
Srimad Bhagavatam Canto 11, Chapter 03, Text 41