In these cases it is usual for the so-called secondary personality to assert itself at moments of intense excitement, especially if they have been preceded by days of worry and fatigue and nights of disturbed rest. The secondary personality is not a complete personality, but is a manifestation of the original ego with the memory for past events as a _tabula rasa_. It is well known that the memory is one of the intellectual faculties most dependent on physical conditions. It is the lowest in the scale of mental qualities and is shared to a very large degree by the animals. Injuries to the head not infrequently produce lacunae in the memory. These lacunae often have very striking limitations. It is not an unusual thing to find that old people remember events of their very early childhood better than things that have happened within a few years. Still more interesting is the fact that languages learned in youth may continue to be easily used, when those that were learned later in life, though perhaps known better than the previously studied languages, are forgotten. It has often been noted that people who suffer from apoplexy may have peculiar affections of their memory. This may include such striking peculiarities as the forgetting of the uses of things, though their names are retained, or more commonly, the forgetting of names while the knowledge of uses remains. The one form of memory disturbance is called "Word Amnesia;" the other is called "Apraxia." It is on {264} record that a person suffering from a hemorrhage in the brain has lost completely the use of a language acquired later in life, though the memory of the native language, long since fallen into disuse, was perfectly retained. One apoplectic woman patient who had left Germany before she was ten years of age, and who had lived in America until she was fifty, forgot absolutely the English she knew so well and had to set herself to work to learn it over again, though her German came back to her very naturally. These are wonderful peculiarities of memory-pathology that show how much this faculty is dependent on the physical basis of mind and upon the cellular constituents of the brain.