ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 399 



Development of Veins of the Liver in the Rabbit and Sheep.* 

 C. Bonne has studied these in a series of embryos from C mm. in 

 length to full term. His main results are : (1) In man, rabbit and 

 cat the right umbilical vein ceases early to share in the hepatic circula- 

 tion, and serves exclusively for circulation in the right abdominal wall, 

 leading down to the left umbilical vein, where it joins the blood from the 

 allantois. In sheep both veins are equal in size, and unite beneath the 

 liver into a common median trunk, which lasts till the pulmonary circu- 

 lation is established. At the 7 mm. stage this trunk gives off numerous 

 branches to the abdominal wall : these disappear later. The fusion 

 of the two veins takes place first in the interior of the liver, or at its 

 level, and progresses downward. The canal of Arantius is continuous 

 at the lower extremity with the common trunk of the two umbilicals. 



(2) The common vitelline trunk is for a long time much smaller than 

 tihat of the hepatic veins ; at 14 mm., as the intestinal develops, it be- 

 comes larger. The vein of Spiegel's lobe first ends in the vitelline, later 

 in the sinus of the portal vein or in a vein of the right lobe. Some 

 veins from the right and Spiegel's lobes go direct to the vena cava. 



(3) In man, rabbit and cat the canal of Arantius is early distinct from 

 the sur-annular segments of the two vitellines ; it exists before they 

 have lost their connection with the proximal ring. It is separated 

 from them by a thickness of hepatic tissue traversed by capillaries. 

 This occurs later in the sheep, viz. after the proximal ring has disap- 

 peared. Then the canal of Arantius gets smaller, to the advantage of 

 the inferior vena cava, which collects the sur-hepatic veins. (4) The 

 efferent veins are at first represented by the terminal trunks of the 

 two vitelline veins. The left vitelline has a communicating orifice 

 with the right efferent vein, which also communicates with the sinus. 

 All this is transitory ; at 8 mm. the two sur-hepatics connect with 

 the great trans-hepatic, not the sinus. Physiological considerations are 

 also discussed in the paper. 



Nephridial Canals in Guinea-Pig. f — R. Meyer finds that the 

 primitive nephridial canals in the guinea-pig have a communication 

 with the coelome, but this seems rather a re-opening of a previous con- 

 nection between the median and lateral plate than a fresh invagination. 

 The openings seem comparable to the secondary nephrostomata in 

 Amphibians, except that those of the guinea-pig are transient. 



Lens Development under Abnormal Conditions.! — A. Schaper 

 has studied the development of the lens in the embryo of Rana after 

 extirpation of the central nervous system. The new lens rudiment he 

 finds grows downwards from its point of origin in such a way as to 

 suggest an " attempt " to get into a normal place with reference to the 

 eye vesicle, which may be, the writer thinks, due to some sort of tropism 

 between eye and lens rudiment. 



Structure and Development of the Middle Ear in Man and 

 Mouse. § — L. Driiner discusses in this paper the question of the homo- 



* Jonrn. Anat. et Physiol., xl. (1901) pp. 225-67 (3 pis.). 



t Anat. Anzeig., xxiv. (1904) pp. 25-30 (4 figs.). 



% Tom. cit , pp. 305-26. § Tom. cit., pp. 257-86. 



