189 



ViTALi, Contributo alio studio istologico dell' unghia etc. Ricerche fatte 

 nel Laboratorio di Anat. norm, della R. Universita di Roma etc., 1906. 



Della Valle, Cl., Contributo alia conoscenza della circolazione san- 

 guigna nella Mucosa nasale del Mammiferi adulti. Ricerche fatte nel 

 Laboratorio di Anat. norm, della R. Universita di Roma, 1901. 



Castellana. (Lavoro di prossima pubblicazione.) 



Zawarykhin, Ueber das Epithel der Tonsillen. Anat. Anzeiger, 1889, 

 p. 467. 



Marcel Labbe e Levy-Sirugue, Recherches sur la Structure des amyg- 

 dales. Bull, de la Soc. anatom., Juillet 1899. 



Nachdruck verboten. 



Amnion Protrusion into tlie Lens-Vesicle. 



By Dr. Otto Landman, Toledo, Ohio, U. S. A. 

 With one Figure. 



A description of the following specimen is of interest because it 

 throws some light on the causation of certain anomalies of the lens. 

 The specimen is that of a chick's eye and some tissue can be seen in 

 the concavity of the lens; moreover the early appearance of this tissue 

 abnorpaally placed may serve to account for an embryological explan- 

 ation of congenital lenticular changes. 



The embryo is that of a chick 69 hours old and hatched at 38 '^ C. 

 It was fixed in Flemming's solution and hardened in the usual way in 

 ascending strengths of alcohol; imbedded in paraffine and cut into 

 series, 7 /.i in thickness. The entire eye was cut into 65 sections and 

 stained in saffranine. 



Five of the sections show the condition to be described: 



The optic- cup has developed normally and the ectoderm has sunken 

 into the cup to form the lens. The lens is in that stage preceding 

 its closure to form a vesicle, and just prior to its separation from 

 the ectoderm. Between its lips dips a part of the amnion with its cells 

 plainly visible and filling incompletely the lens -pit. The ectodermal 

 layer limits the mass and contains two nucleated cells whilst a third 

 cell lies on the membrane; within the sac thus formed lie three large 

 spherical yolk masses, deeply stained, surrounded by yolk - detritus. 

 In the region above the lens, what is striking, is an excessive and 

 unusual accumulation of yolk-masses, some of which have wandered into 

 the protrusion of the amnion. The ectodermal layer of the amnion 

 can readily be traced outwards where it is continuous with the amnion 

 proper. 



