468 journal of Comparative Neurology and Psychology. 



fications necessitated by the recent studies on neuro-fibrillae. No mention is made 

 of the cytological characteristics of the cell body or of functional changes in the 

 neurone. 



Next follow 123 pages (Chapters 5 to 13) devoted to the functional divisions of 

 the nervous system. First, the functional divisions are defined and tabulated. 

 Then they are taken up seriatim, described in detail and the phylogenetic history of 

 each is sketched. These chapters are of great value. The treatment is unique and 

 gives the character to the w^hole work. Among other useful illustrations, there is a 

 series of diagrams of the peripheral nerve components, taken from the literature, 

 and a similar series of original diagrams of the central conduction pathways of each 

 functional system of components. The mastery of these simple diagrams gives 

 the student the principal landmarks for all of his subsequent study of the vertebrate 

 brain. 



The conflicting accounts and chaotic nomenclature of these connections in the 

 lower vertebrates are harmonized and brought into relation with the conditions in the 

 human brain as far as possible. Our knowledge of the structure of the lower brains 

 is still so imperfect that much of this correlation is necessarily theoretical, and it is 

 too much to hope that all of Johnston's homologies will stand the test of time. It 

 can fairly be claimed that the evidence for them is good as far as it goes, though it 

 must be kept in mind that the demonstration is not equally convincing in all cases. 

 For instance, in the somatic sensory system, the demonstration of the genetic rela- 

 tions of the dorsal cornu, funicular nuclei, substantia gelatinosa Rolandi, tubercu- 

 lum acusticum and cerebellum may be regarded as proved. The homologies of the 

 somatic sensory column in front of the cerebellum are by no means so well estab- 

 lished. The probability that the tectum opticum belongs here is strong; but the 

 evidence for the addition of the retina, nervus terminalis and neopallium to this list of 

 somatic sensory structures is still very defective. The visceral sensory column has 

 suffered less modification of the primitive relations in the upper regions of the brain 

 and the homologies of these centers may be regarded as established in a broad way, 

 about as Johnston describes them, from the olfactory bulb to the intermediate zone 

 of the spinal cord, though here, also, the pre-cerebellar connections are by no means 

 so clearly defined as the post-cerebellar. 



Chapter 13 is devoted to the sympathetic nervous system, and the remainder of 

 the book (pp. 218 to 360) to the centers of correlation. The brief introductory 

 chapter (14) contains some of the most important generalizations in the book. The 

 substantia reticularis (a derivative of the central gray) is recognized as the starting 

 point for all of these centers, which make up by far the greater part of the brains of 

 all higher animals. "In the lowest vertebrates, cyclostomes, a large part of the sub- 

 stantia reticularis of the brain remains in its primitive indifferent condition; few 

 special nuclei are developed and the activities of the animal are correspondingly 

 simple." The following chapters illustrate the author's views of the way in which 

 this indifferent material has been shaped in response to the varying functional needs 

 of the successive types of vertebrates. Special attention is called to the value of the 

 teleostean fishes in elaborating type schemata of the vertebrate plan of the several 

 functional units. 



In the sketch of the phylogenetic history of the cerebellum, which is quite com- 

 pletely elaborated, there are several new features, notably in the history of the cere- 

 bellar hemispheres, whose antiquity is established. The chapter on the mesen- 



