22 VASCULOGENESIS IN THE CAT 



Selbst auf dem Dottersack sind solche Gefasse, welche in loco ent- 

 standen sind, nicht zahlreich, denn sie entstehen nur an den Stellen der 

 sogenannten "Anlagen," und die Hauptmasse des Kapillarplexus des 

 Dottersacks entsteht durch Ausbreitung und reichliche Anastomosen- 

 bildung von den primaren Gefassen aus. 39 



Further, the description by McWhorter and Whipple 40 of the 

 to and fro movement of red porpuscles after the heart had begun 

 to beat and prior to the establishment of the circulation points 

 to their confinement in separate compartments. Their subse- 

 quent abrupt entry into the blood stream, must mean the giving 

 way of the wall of the vesicles and their confluence to form 

 vessels all which is consonant with the data obtained from sec- 

 tions and reconstructions, and seems to afford a basis of inter- 

 pretation for an interesting observation of Loeb's: 41 



It turned out in my experiments that the heterogeneous hybrids 

 between bony fishes formed eyes, brains, ears, fins and pulsating hearts, 

 blood and blood vessels, but could live only a limited time because no 

 blood circulation was established at all in spite of the fact that the 

 heart beat for weeks or that the circulation, if it was established at all, 

 did not last long. 



. . . . I succeeded in producing the same type of faulty embryos 

 in the pure breeds of a bony fish (Fundulus heteroditus) by raising the 

 eggs in 50 cc. of sea water to which was added 2 cc. one one-hundredth 

 per cent, NaCN. The latter substance retards the velocity of oxida- 

 tions and I obtained embryos which were in all details identical with 

 the embryos produced by crossing the eggs of the same fish with the 

 sperm of remote teleosts, e.g., Otenolabrus or Menidia. These embryos, 

 which lived about a month, showed the peculiarity of possessing a beating 

 heart and blood, but no circulation. 



These findings of Loeb can hardly be reconciled with the doc- 

 trine that the vessels of the embryo have a primitive continuity 

 of lumen with those of the yolk-sac, for it is inconceivable that in 

 such circumstances, a beating heart could fail to effect a circu- 

 lation. They are however corroborative of the observations of 

 McWhorter and Whipple which would lead us to interpret the 

 condition as a Hemmungsbildung due to failure of concrescence 



39 1912, In Keibel u. Mall. Entwickelungsgesch. d. Menschen, Bd. 2, p. 552. 

 40 1912, Anat. Rec., vol. 6, p. 121. 

 41 1912, Pop. Sci. Mo., vol. 80, p. 5. 



