45-t Anatomy and Development of Veins of Chelonia 



(lition and to a large extent gets rid of the muscular contractions. The 

 best results were obtained when the turtle was killed several days before 

 the injection was made. "A gelatin injecting mass was used in most 

 cases. In order to prevent the cooling of the gelatin before all the veins 

 were filled, the specimens were placed in warm water several minutes 

 before injecting. This is not necessary, however, if potassium iodide is 

 used to lower the melting point of the gelatin. For the purpose of 

 studving more exactly the relations of the veins in the liver and the 

 kidneys, some of the turtles were injected with Huntington's, 97, wax 

 injecting mass and corroded with concentrated commercial hydrochloric 

 acid. By injecting the liver through the precava with one color and 

 through the abdominal vein with another, it is possible to distinguish 

 the advehent from the revehent systems even to their finest branches. A 

 few of the larger snapping turtles were injected with the common starch 

 injecting mass. 



About fifty turtle embryos were studied for the development of the 

 veins. Kinosternon pennsyhanicum was the species chosen for embryo- 

 logical investigation because it was possible to obtain a more complete 

 series of this than of any other form. The more important stages were 

 also studied in Chrysemys picta. For purposes of comparison several 

 embryos of the common lizard, SceJoporns undulatus, as well as chick 

 embryos of various stages, were examined. 



Most of the material had been fixed in picro-siiblimate or picro-nitric. 

 The picro-sublimate material was, as a rule, satisfactory both as to fixa- 

 tion and for the subsequent staining reactions. On the other hand, not 

 much can be said in favor of picro-nitric either for fixings the tissues, or 

 for preparing them for the stain. The embryos were dehydrated, 

 cleared, and embedded in paraffin according to the usual methods, and 

 serial sections were cut about 20 fi thick. Several methods of staining 

 were tried, but the best result? were obtained with Delafield's h hema- 

 toxylin and picric acid. After picro-sublimate fixation this combination 

 differentiates the blood vessels very clearly. Frontal reconstructions, in 

 whole or in part, were made of the venous system of all the embryos 

 studied. Wax reconstructions were made wherever deemed necessary. 



HISTORICAL SKETCH. 



The literature dealing with the embryology of the venous system of 

 Chelonia is very fragmentary. Eathke, 48, and Agassiz, 57, are the 

 only investigators that have hitherto made any attempt whatsoever to 

 even superficially sketch the development of the veins of this interesting 

 reptilian form. Agassiz gives as a reason that so little is known about 



