No. 377-] REVIEWS OF RECENT LITERATURE. 361 
The ventral nerve cord grows forward into the above mass as nerve 
fibers accompanied, probably, by some cells from the old cord. It is 
interesting to note here that the entire cord, at least as far back as 
the fifteenth segment, shows most active mitotic divisions of ganglion 
as well as of other cells. To this forward growth from the old cord 
is added a collection of many cells that migrate in, separately, from 
the new epidermis that grew over the cicatrix. These cells furnish 
the main part of the new brain. 
The new epidermis over the cicatrix grows backward as a small 
funnel, which meets the old intestine as it elongates into the new 
tissue. The ingrowth ultimately opens into the old intestine and is 
thought probably to form the digestive tract in the new head as far 
back as the fourth segment, where the new pharynx will be formed — 
from the old intestine. 
The making of a new head in the earthworm thus involves aan 
tion of old organs, transformation of some of them, and in the case 
of the nervous system marked change of activity even in parts remote 
from the wound; in addition there is a large element of new formation 
from cells of an embryonic and undifferentiated character. 
A. À. 
Two Papers on the Finer Structure of Nerve Cells. — Students 
of neurology are indebted to Prof. A. van Gehuchten for an excellent 
résumé‘ of the more recent work on the finer structure of the nervous 
cell. The paper was prepared as a report for the Twelfth Inter- 
national Congress of Medicine, held at Moscow in August, 1897. 
After a brief introduction the subject is dealt with in four chapters 
as follows: the internal organization of nervous cells, changes which 
accompany their different states of activity, changes from lesion of 
the axis-cylinder process, and changes from disturbances in the 
circulation and from poisons. The paper is illustrated by one plate, 
and the numerous bibliographical references are gratifying. It is to 
be regretted that the medical influence has asserted itself to such an 
extent that the report treats almost exclusively of the nervous cells 
of vertebrates. 
Prof. C. F. W. McClure? has undertaken the study of the finer 
Structure of the nerve cells in the invertebrates on lines inaugurated 
1 Gehuchten, A. van. L’Anatomie fine de la cellule nerveuse. Za Cellule, 
2 McClure, C. F. W. The Finer Structure of the Nerve Cells of Javertebrates. 
I. Gasteropods. Zool. Jahrb., Abt. f. Anat. u. Ontog., vol. xi, 189 
