ON THE TRANSITORY OR ARTIFICIAL FISSURES OF THE 
HUMAN CEREBRUM. 
BY 
FRANKLIN P. MALL. 
Professor of Anatomy, Johns Hopkins University. 
WirTH 1 TABLE. 
Nearly a century ago J. F. Meckel’ discovered the transitory fissures 
in the cerebrum of human embryos eight or nine weeks old; these he 
believed to be normal and in no way connected with the permanent 
fissures. The presence of the transitory fissures was confined by numer- 
ous competent anatomists and from time to time their relation to the 
permanent fissures was discussed. According to Tiedemann they repre- 
sent the earlier stages of the permanent fissures, and Cunningham 
states that most of them are obliterated while several ‘“‘ occupy positions 
which later.on are occupied by permanent fissures, and either show 
direct continuity of existence with these, or at least act as their pre- 
cursors.” 
It was gradually shown that the transitory fissures are usually present 
in embryos of the third and fourth months. To be sure suitable material 
for study is difficult to obtain and usually the specimens studied were 
those that had been preserved in alcohol for a considerable time. The 
influence of alcohol, especially weak alcohol, upon tissues is well known 
and this naturally led Bischoff in 1868 to suspect that the transitory 
fissures were artificial, having been produced by the macerating influ- 
ence of weak alcohol. Furthermore, he found that the fissures were 
not present in the brains of embryos which had been hardened in chloride 
of zinc. ‘This view is accepted by Marchand (1891) in his paper on the 
corpus callosum. 
Were it not so difficult to obtain fresh human embryos, this question 
would have been settled long ago. That these fissures are normal seems 
to be proved by Ecker, in 1869, who observed their presence in the fresh 
1References to the literature upon this subject will be found in the following 
papers: Cunningham, Jour. of Anat. and Phys., XXIV, 1890; Hochstetter, Biblio- 
theca medica, Stuttgart, 1898; and Retzius, Biol. Untersuch., X, 1902. 
