Susanna Phelps Gage 429 



Zimmermann " in rabbit and cliiek shows 2 in the fore-brain, 3 in the 

 mid-brain, 8 in the hind-brain, and 4 in connection with the accessorius 

 nerve. Froriep " found in the mole 3 in the diencephal, 3 in the mid- 

 brain, which disappear later, and 7 in the hind-brain, the last being 

 connected with the vagus nerve. Schultze *" figures folds in the pig. 

 Lewis " and Minot " show four neuromeres in the oblongata of the pig. 

 Bradley " is the latest investigator to study these folds in the pig, finding 

 7 in the hind-brain, the 1st belonging to the cerebellum and the 7th con- 

 nected with the Xth nerve. 



Total Folds in Homo. — Kupffer "" merely mentions in a human embryo 

 of three weeks, five pairs of total folds in the oblongata. His " shows 

 that in the region of the oblongata, certain folds in disappearing, leave 

 behind cell-nests as in the olive. However, in his monumental work on 

 human embryology," he seems to have avoided giving any hint that such 

 structures exist, while in his models of early specimens, a glittering 

 smoothness occurs in regions which are really full of significant form. 

 In models of human embryos made in Dr. Mall's laboratory, certain facts 

 shown in his specimens were avoided since they did not bear on the 

 subjects he was investigating. However, this seems to be a case where a 

 little positive evidence more than counterbalances a vast amount of 

 silence. 



Granting the existence of total folds in the neural tube of mammals 

 at certain stages of development, the question has been put, are they 

 artifacts due to shrinkage of the mesoderm ? In answer I would say : — 

 1st. The crowded cellular growth of the neural tissue and the scattered 

 cells of the mesoderm would seem to indicate that though the latter might 

 shrink away from the neural tube, it would not throw it into such sharp 

 foldings as occur. Direct observation seems to corroborate this argument. 

 2d. The folds are found at the margins of the neural plate in man before 

 the mesoderm has grown up to this margin. 3d. In lower mammals 

 corresponding in general to this human specimen, the mesoderm as far as 



" Zimmermann, W., Anat. GeselL, Verhandl. 5, 1891. 



*'^ Froriep, A., Anat. Gesell., Verhandl. 6, 1892. 



** Schultze, Oscar, Grundriss der Entwicklungsgeschichte des Menschen u. 

 der Saugethiere. Leipzig, 1897. 



" Lewis, F., Amer. Jour. Anat., II, 1903. 



*' Minot, C. S., Laboratory text-book of Embryology. Phila., 1903. 



" Bradley, 0. C, Rev. Neurol, and Psychiatry, II, 1904. 



=" Kupffer, C, Konig. baierische Akad. der Wiss., Math.-Phys. CI., Sitz. 

 XV, 1885. 



" His, W., Konig. sachs. Ges. d. Wiss., Abhand. d. Math.-Phys. Klasse, 

 XVII, 1890. 



