194 D. DAVIDSON BLACK 



V. Moiiakow's laboratory (17). In the case reported by him, how- 

 ever, the condition of cyclopia was much complicated by the 

 presence of a very extensive malformation in connection with the 

 brain stem and cord, which without doubt was quite independent 

 of the cyclopian condition. 



With the exception of a moderate degree of hydrocephalus, 

 the present case presents no malformations other than those 

 which may safely be considered as due to the cyclopic condition. 

 Such being the case, this material is well adapted to determine 

 among other things, whether the cyclopian brain can in any way 

 be regarded as an arrest of development at an early phylogenetic 

 stage, as Naegeli suggests. The research was begun in the hope 

 of clearing up this point, and as will be shown, all the evidence 

 in this case is against the assumption of such a reversion. 



The central nervous system is of paramount interest in this 

 case, and the necessarily incomplete general description is only 

 warranted in so far as it records certain data which may be of 

 use in any future complete investigations. In the course of the 

 work, the condition of development in the pallium has proved 

 to be of the greatest interest, as it tends to throw additional 

 light on the subject of the evolution of the normal cortex. This 

 phase of the research has not been as fully dealt with here as is 

 desired, and will be the subject of a future communication. 



The cyclopian foetus, upon which the following observations 

 have been made, was obtained in Chicago through the courtesy 

 of Dr. Warren H. Hunter, Cook County Coroner's Physician, 

 and Prof. E. R. Le Count of Rush Medical College, Chicago. 

 The clinical details of the case have already been reported by 

 Dr. Harry Jackson (11). 



I am indebted to Prof. C. J. Herrick for the opportunity of 

 taking up this work and for much helpful criticism throughout 

 the investigation. The work was begun in the Anatomical De- 

 partment of the University of Chicago in the spring quarter of 

 1910. The major portion of the technique in connection with 

 the microscopic study of the central nervous system and also the 

 examination of this material has been done in the Anatomical 

 Department of Western Reserve University. 



