20 C. W. M. Poyfiter 



ducted along wrong lines." " No constant or definite difference 

 can be detected in that area of the cortex associated with speech 

 centers on the two sides, and yet only the left is functional." 

 Giacomini (1881), from an extensive study, was able to find no 

 psychical significance in the variations between the two sides, and 

 makes the general conclusion, " Le anomalie morfologiche degli 

 organi pari o delle loro parti prediligono il lato sinistro." 



The so-called transitory fissures, which appear about the third 

 month, have been described by many observers, and were made 

 the subject of very careful study by Cunningham (1892), who 

 considered them of morphological importance and was influenced 

 in many of his conclusions by them. Bischoff (1868) was the 

 first, I believe, to express doubt as to their manner of origin. 

 Again Marchand (1889), while accepting the fissures which ap- 

 pear on the mesial surface of the hemisphere, doubted the exist- 

 ence of such on the lateral surface. Hochstetter (1898) ex- 

 pressed very positively the belief that all so-called transitory 

 fissures were the result of decay or the action of the hardening 

 fluids. Retzius (1902) reported a 55 mm. embryo which had 

 been obtained under very ideal conditions and which was most 

 perfectly preserved, showing a perfectly smooth cerebral surface. 

 Mall (1902) concluded from his observations that the condition 

 was produced post mortem. 



Symington (1901) was not in accord with the views of Hoch- 

 stetter, and showed that these fissures were present in preserved 

 material. Smith (1904c) dismissed the whole question as settled 

 in the negative by the work of Goldstein, Mall, and Retzius. 



The etiology of the permanent fissures of the human cerebral 

 cortex of man and the influences which tend to determine their 

 arrangement are quite fully reviewed by Chiarugi (1886) and 

 Saporito (1901). The former concludes that the cerebral con- 

 volutions have their principal origin in the disproportion of the 

 brain in front to the cavity of the skull and the reciprocal mechan- 

 ical influence from the various parts of the brain; it is through 

 heredity that the modifications so produced in the condition of the 

 cerebral surface are transmitted, accumulated, become constant 

 and independent of the first determining cause. Special mechan- 



364 



