During the last decade research on neural transplantation in mammals has grown extensively, and has attracted the attention of many young inquisitive scientists. This growth, as the critics point out, has been somewhat random, and has resulted neither in the formulation of basic concepts nor in any other significant achievement. For instance, they question-how is it possible to jump into functional research with clinical bearing when the basic morphological work has not yet been conducted? The criticism, objectively speaking, is valid and is supported by the fact that every investigator who has stepped into this unex plored field of neurosciences has formulated questions in his own way, has followed his own "model" oftransplantation, and has arrived at his own unique conclusions. The potential danger, as the critics emphasize, in this type of approach lies in that instead of evolving into a scientifically solid and valuable field of research, it may end in a confusing and conflicting mass of questionable claims and subjective opinions. The present situation, very likely, is a reflection of unrestrained enthusiasm and imaginativeness of the investigators, and the demands of the times for the so-called "newsworthy" and "breakthrough" publications. Despite these limitations, two important facts have been estab lished in this field. First, as far as transplantation of neural tissues per se is concerned, what was considered impossible by some critics about 10-12 years ago has been shown to be possible."

The presence of nerve cells in the white matter of the spinal cord and in the spinal and cranial nerves has attracted the attention of some researchers in the past. Because of their location in such unexpected regions, these neurons provided a rich field of speculation regarding their nature and function. This was partic ularly true about the nerve cells lying in the spinal white matter. From phylogenetic considerations, neurons in the spinal white matter are present more abundantly in amphibians, reptiles and brids than in mammals. A. brief survey of literature on lower vertebrates indicates that GASKELL (1885, 1889) was the first to describe the displaced neurons in the white matter of the spinal cord of alligators and various species of birds. In his consideration they were displaced ganglion cells. In 1902 von KOELLIKER gave an exhaustive account of such neurons in the white matter of the spinal cord of reptiles and birds. In these animals he observed clusters of such neurons running in longitudinal columns and thus was able to group them into nuclei known as "Hofmann's nuclei." Further, he suggested that these nuclei arise from the mass of the ventral horn and that they may give rise t. o preganglionic fibers, motor fibers or ventral commissural fibers. In t. he ensuing years investigation of these nuclei was extended by STREE TER, KRAUSE, TERNI, HUBER and others (quoted from ARIENS KAPPERS et. aI., 1960, Vol. I, p. 206-210)."