The complete fissures of the human cerebrum, and their significance in connection with the growth of the hemisphere and the appearance of the occipital lobe / by D.J. Cunningham.

  • Cunningham, D. J. (Daniel John), 1850-1909.
Date:
[1890?]
Catalogue details

Licence: Public Domain Mark

Credit: The complete fissures of the human cerebrum, and their significance in connection with the growth of the hemisphere and the appearance of the occipital lobe / by D.J. Cunningham. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    Richter I have also found useful, although those which we com- mooly see in our text-books, and which have been taken from Ecker and Mihalkovics, cannot be regarded as giving a proper idea of the transitory furrows as they exist during the period of their maximum development. Duration of the Transitory Fissures.—The mesial wall of the hemisphere is considerably thinner than the outer wall, and it is partly in consequence of this that the transitory fissural in- foldings first make their appearance upon it. But we have the most conflicting statements regarding the actual period at which they first begin to be formed, and also regarding the time at which they vanish. These views will best be understood if I place them in tabular form :— Duration of Transitory Furrows. Authority. Period of Appearance. Period of Ohliteration. Meckel. 8 th to the 9th week. Schmidt. Middle of the 3rd mouth. End of the 4th month. Ecker. 3rd to the 4th month. Commencement of the 5th month. V. KoUiker.i 3d month. 5th month. Mihalkovics. Middle of the 3rd month. Commencement of the 4th month. Romiti. 10th week. End of the 4 th month. We may remark here that the description given by Schmidt hardly agrees with his figures, because the transitory fissures are indicated by him on the mesial surface of a cerebrum taken from an embryo at the eighth week, which bears out the original observation of Meckel. The difference of opinion which is shown in the above table results no doubt very largely firom variations in the duration of these fissures, but it is likely that it is also in a great measure due to the almost insuperable difficulty of giving to an embryo its proper age. As I have stated, the embryos which I have specially studied with the view of obtaining a knowledge of the transitory fi.ssures ranged from about the third month to about the end of the fourth month. In all of these the transitory fissures were visible. Clearly Mihalkovics is wrong in limitiug the time of their existence to one fortnight. It appears equally ' ErUickklungsgeschichle des Menschm und der h'dheren Thiere., 1879.