Licence: Public Domain Mark
Credit: The works of John Hunter / edited by James F. Palmer. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![But the moment a new mode of action takes place, actions arising from sensation must be performed for the support of this; and an ani- mal must die if these sensations are not produced, which cannot be produced if there is no brain*. Actions arising from the union of the two principles, life and sensa- tion, are extremely evident; being all those actions which constitute a state of mind, or those feelings of the mind from which instinct arises. Sleep.—A singular result of our being possessed of the sensitive principle is sleep. Perfect sleep is an annihilation of the power of present sensation, of the power of thinking, and all traces of the past, or what we call memory. We find that there is, of course, a cessation of all voluntary actions; the will itself is in every respect at perfect rest, and we are at this time, in respect to ourselves, in a state of non- existence. But sleep has its degrees; perhaps in all cases there is a considerable loss of these principles, especially sensation ; but the effects of sensation are not always lost, namely, those operations of the mind which produce actions which are very nearly voluntary. During sleep, therefore, the mind may be thinking, which forms what we call dreams; but as our present sensations do not become directors of those actions which the mind is employed about, no such action takes place as the mind forms to itself. It is even possible to dream when awake; it is only necessary for the thinking power to take possession of the mind, and proceed with an action with which the present sensation has nothing to do, so that a person neither sees objects, hears sounds, nor feels anything that touches him ; and when the mind ceases to act and sensation returns, we call it a dream. Now whenever the body loses type of inferior animals, but afterwards advance to those which are still higher and higher in the zoological scale. Hunter in the main was well acquainted with this law of development as regards the higher animals, as will appear from the following passage, in which we may remark that he has anticipated many of the leading discoveries on this sub- ject by modern anatomists. The passage occurs in the introduction to the description of the drawings relating to incubation. “ If we were capable” (he says) “of following the progress of increase of the number of the parts of the most perfect animal, as they first formed in succession, from the very first, to its state of full perfection, we should pro- bably be able to compare it to some one of the incomplete animals themselves, of every order of animals in the creation, being at no stage different from some of those inferior orders; or, in other words, if we were to take a series of animals, from the more im- perfect to the perfect, we should probably find an imperfect animal, corresponding with some stage of the most perfect.” (Hunt. Cat., Phys. Series, vol. ii. p. iv.) Many other passages might be adduced which evince that Mr. Hunter’s extensive acquaintance with comparative anatomy had enabled him to deduce the true principles which regu- late the formation of the body and the coexistence of the different systems of parts in the same individual organism.] * [Mr. Hunter must have been aware of many examples of foetuses without brains which have lived for some time after birth. He must here mean the medulla oblon- gata, without which respiration cannot take place.]](https://iiif.wellcomecollection.org/image/b21996623_0001_0295.jp2/full/800%2C/0/default.jpg)
