33 



ion, have regarded the formation of the linea Douglasii as an 

 independent process, because they were not acquainted with the 

 considerations communicated above, from which appears tiiat the 

 formation of the linea is but part of a more comprehensive process, 

 whicii takes ])lace in the rectal sheath. 



Among the diffei'ent tiieories tliat have been suggested about the 

 signification of the linea Douglasii. that of Gkgknbaur has become 

 most generally known. His hypothesis, in which the views of RtTZius 

 and Hrnle are united, makes the Vesica urinaria and the Vasa 

 epigastrica inferiora responsible for the occurrence of the linea 

 Douglasii. 



Objections have been made against this theory and against tliose 

 of Doi'fiT,AS and of .Soi.<;kh. from which oiijections we must conclude 

 that these hypotheses nvc incorrect. Only the theory of Eislkk '), 

 which is supported l)y the results of ontogeny and comparative 

 anatomy, stands unaltarked al the present moment. Eislkr seeks the 

 cause of the formation of the linea in (he protuberation of the anterior 

 abdominal wall, indicated as processus vaginalis, because this processus 

 compels the libres of the Mnsculi obliq. int. and fransversus, which 

 run cranially from the proce.ssns behind the M. rectus to give way 

 ventralwards tiiere. wiiore tlio processus is, and to remove before 

 the M. rectus. 



It is obvious that the hypothesis of Eislkr cannot be correct, for 

 it tries likewise only to tiud a cau.se for the piercing of the M. 

 transversus liy the M. rectus; like all other theories previously 

 suggested, it regai-ds the formation of the linea Douglasii as an inde- 

 [)endeiit process, whilst it must only be regarded as the last phase 

 of the piercing process that takes |)lace in the rectal siieafh. 



It is conse()ueutly completely irrational to indicate for the formation 

 of the linea Douglasii a cause that does not explain at the same 

 time the other modifications occuriing in the construction of the 

 sheath. The (|iiestion about the cause of the linea semicircularis 

 must be replaced by the question about the inclination of the M. 

 rectus to pierce the three elements, that originally formed the posterior 

 lamella of the sheath of the M. rectus. Further investigations will 

 perhaps give an answer to this question; for the present moment 

 only the fact of the piercing can be ascertained. 



1) In P. EisLER. "Ueber die nachste Ursache dei- Ijiiiea semicircularis Douglasii 

 Yerhandl. der Anat. Gesellscliaft f898"' one finds described all the theories about 

 the cause of the linea, indicated here. 



3 



Proceedings Royal Acad. Amsterdam. Vol. XVIU. 



