The dreams of the blind and deaf have been investigated by Prof. Jastrow.1 Prior to Jastrow, Heermann had considered the subject; the studies of both, taken up independently, were practically identical in their results.

According to Jastrow, those totally blind from birth or prior to the fifth year do not see in their dreams. If blindness occurs between the fifth and seventh years vision in dreams may or may not be present. This is due to the fact that prior to the seventh year the visual centre in the brain is developing; its growth depends upon the supply of sensations reaching it by way of the eyes. If blindness occurs these sensations are cut off and the visual centre degenerates. Between the fifth and seventh year "the preservation of visualizing power depends on the degree of development of the individual. If the faculty is retained, it is neither stable nor pronounced. If sight is lost after the seventh year the sight centre can maintain function, and the dreams may be hardly distinguished from those of a seeing person."

The dreams of the blind are apparently commonplace, probably because the absence of sight does not tend to cultivate a vivid imagination, and because the knowledge gained by the blind is realistic. Ghosts, elves, fairies, monsters, etc., do not figure so much as in the dreams of the sighted. When the blind dream of ghosts they either hear them or are touched by them; the ghost pursues the victim, humming and groaning as it runs, or it has a rough voice, or its bones rattle.

1 Fact and Fable in Psychology, 1900, Houghton, Miffin & Co.

Hearing is the most important sense. Beading raised type with the fingers almost never occurs in dream life. "The boys dream of playing, running, jumping, and so on; the men of broom-making, piano-tuning, teaching and similar work; the girls of sewing, fancy work, household work, and the like."

Dr. Heermann found, as a result of post mortem studies of ten cases, that the optic nerves degenerate after about twenty years of blindness. A case is recorded of vision in dreams being maintained for fifty-two years, another for fifty-four, then fading out. It is seen, therefore, that the ability to visualize is not dependent solely upon the integrity of the optic nerves.

Persons born blind and deaf have these senses absent in their dreams. The same faculties as are utilized during the day appear in the dream world; talking with the fingers is present. As with the blind, the critical age for the deaf is from the third to the seventh year. If deafness occurs between these years hearing may or may not be present in the dreams; if deafness occurs after the seventh year hearing will appear in the dreams.

In Jastrow's book is given in more or less detail the dream-life of the famous Helen Keller and Laura Bridg-man.