208 
the gill function. In neither case would there be any physiological reason 
for the separation of the blood issuing from the conus. If the gills in the 
fish do not entirely oxygenate the blood, and in some fish the fins apparently 
assist in oxygenation, then the fish blood really corresponds to our notion 
of ‘the mixed blood” (not fully oxygenated) in the higher forms. Here 
again is a problem upon which no definite information may be given. 
In conclusion, my position on the quality of blood circulating in the 
arteries of the vertebrates is that it is what may be termed “mixed” in 
all forms from the embryo mammal and bird to the fish, and if there have 
been advanced various theories on the mechanics of the passage of the 
blood through the heart of a given form they have been based on the alleged 
physioiogical necessity for a better quality of blood circulation in the head. 
In other words the systemic arteries convey arterial blood only in the 
mammal and bird after birth. I believe if one eliminates the idea that 
the head must receive a better quality of blood (Sabatier scheme) the 
whole doctrine of the character of the circulation in all forms of verte- 
brates is not only simplified but placed upon a sound physiological and 
developmental basis. 
LITERATURE. 
ee runer, (Ei, 
On the heart of lungless Salamanders, Jr. of Morph., Vol. XVI, No. 
2, 1900. 
2. Gasch, F. R., Klassen und Ordnurgen des Thierreichs, Vol. 6, Sect. 4, 
p. 768. 
3. Lillie, F. R., Development of the Chick. Henry Holt, 1908. 
4. Parker and Haswell. Manual of Zoology, 1900, p. 422. 
5. Pohlman, A. G. 
The course of the Blood through the Heart of the Fetal Mammal. 
Anat. Rec., Vol. III, No. 2, 1909. 
6. Wiedersheim, R. 
Comparative Anatomy of Vertebrates. Macmillan, 1907. 
=I 
Ziegenspeck, JR. 
Die Lehre von der doppelten EKinmiindung der unteren Hohlvene in 
die Vorhéfe des Herzens. Samml. Klin. Vortriige, Ser. XIV, Heft 
II, No. 401. 
