ayeff/' all of which agree with the present case in general [98] 

 structure but differ from it in the absence of muscle. In 

 two other cases, however, described by Pyatnitzki and Ger- 

 lach/* respectively, striated muscle fibres were found, and it is 

 to be assumed that such tissue was present in Neumayer's 

 case, for the tail in this instance could be excited to reflex 

 contraction by stimulation of the sacral region. The compli- 

 cated arrangement of the muscles found in some instances is 

 associated with the occurrence of bone, as in the case de- 

 scribed by Hennig and Kauber,'" and especially in Kohl- 

 brugge's case.'^ The tail described by Gerlach in a foetus of 

 4.6 cm. also contained a continuation of the notochord, which 

 has as yet never been seen in older subjects. 



The Tail in the Human Embryo. 



The caudal region in human and other mammalian embryos 

 has already been described by Ecker, His, Keibel, Fol, Braun 

 and others. These accounts, while agreeing in the main, 

 bring out considerable differences of opinion as to details. 

 For this reason I give here a further description of the tail 

 region in several human embryos. This I am enabled to do ^99] 

 through the kindness of Dr. Mall, who placed at my disposal 

 his fine collection of human embryos. Two specimens, four- 

 teen and sixteen millimeters long respectively, were found to 

 be especially adapted for this purpose, for it is at this stage 

 that the tail reaches the highest point in its development. 

 The study of these was greatly facilitated on account of their 

 excellent state of preservation, and by the fact that they were 

 cut into perfect series of sagittal sections. 



Beriicksichtigung der caudalen Anhiinge des Mensclaen. Inaug.-Diss., [98] 

 Freiburg i. Br., 1898. 



22 W. Scheboldayeff : Tailed Men. Zemsk. Vracli, vol. vi, 1893 (Russian). 



23Inaug.-Diss., St. Petersburg, 1893. 



24 L. Gerlach : Ein Fall von Scliwanzbildung bei einem menschlichen 

 Embryo., Morpbol. Jahrb., Bd. vi, 1880. 



25 C. Hennig and A. Rauber : Ein neuer Fall von geschwanztem Men- 

 schen. Virchow's Archiv, Bd. 105, 1886. 



26 Natuurkund. Tijdschr. v. Ned. Indie, Deel. Ivii, 1898. 



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