DEVELOPMENT OF PRIMITIVE BLOOD-VESSELS. 91 



becomes the cavernous sinus. The rest of the dural sinuses come from branches 

 of the primary head-vein. The sinuses of the mid-dorsal line arise from the 

 anastomoses of the veins of the two sides; the basal sinuses arise for the most part 

 from veins which border the Gasserian ganglion and the otic capsule. 



In 1916 Stracher published an article on the veins of the head of the chick, 

 in which he deals with the fate of the vena capitis medialis and the origin of the 

 vena capitis lateralis. In this work he uses the method of reconstruction in 

 preference to the method of injection in a form in which it is easy to obtain 

 abundant injected material, on the ground that with reconstructions the relations 

 to the surrounding tissues can be better analyzed. Stracher's own work, however, 

 suffers from the limitations of his method. His reconstructions show the larger 

 trunks, which are not always the most important ones, and do not show certain 

 tiny channels which are essential to an understanding of the relations of the vessels. 

 He shows the stage at which the primitive vessel of the hindbrain (vena capitis 

 medialis) and the primary head-vein are both present in the same specimen and 

 equal in size. This had not been done previously, and is an important point. 

 He also shows in part how the middle segment of the primary head-vein arises, 

 but misses several points that are essential to an understanding of this vein. In 

 his text-figure 2, from a chick of 30 somites, he shows a short branch from the 

 anterior cardinal vein and a branch from the maxillary (ophthalmic) veins, and 

 recognizes that these two branches become connected and form the vena capitis 

 lateralis. He speaks of the branch from the inferior orbital vein (my maxillary 

 vein) as arising from a swelling on the vena capitis medialis, not realizing that 

 it is a new outlet, not for the blood of the vena capitis medialis but for the blood 

 of the primitive cerebral vein, as is plainly shown in plate 6. In discussing the 

 origin of the vena capitis lateralis from the lower border of the Gasserian ganglion 

 to the anterior cardinal vein he says (page 55) : 



Kastschenko gibt kerne Abbildung, die ihre Entstehung zeigen wiirde, seine Tafel 

 stellt sie da, nachdem ihre Ausbildung vollendet ist. Nach seiner Schilderung "durch- 

 schneiden" die Nerven die Vene. Demgegeniiber ist zu betonen, dass der eben geschil- 

 derte Teil der Vena capitis lateralis es folgt spater noch die Ausbildung weiterer caudal 

 and cranial davon gelegener Strecken frei im Gewebe, ziemlich entfernt von der Vena 

 capitis medialis entsteht. 



Thus he realized a part of the method of origin of the vena capitis lateralis, 

 but missed entirely its relation to the capillaries of the visceral arches. In regard 

 to the relations of the portion of the primary head-vein in the region of the 

 Gasserian ganglion, Stracher's models are better than his interpretations. The 

 essential facts are that the vena capitis medialis is a vessel on the hindbrain, the 

 vena capitis lateralis is a more superficial vein which lies ventral to the hindbrain; 

 both are present in the same specimen at a given stage; both are mesial to the 

 Gasserian ganglion, one as a part of the system of vessels of the pia mater and the 

 other as a part of the primary head-vein. 



Stracher shows both the vena capitis medialis and the vena capitis lateralis 

 in their correct position mesial to the Gasserian ganglion, and then concludes 



