Anatomy. — "Thymus, spiracular sense organ and fenestra vestibrdi 

 [ovalis) in a 63 m.in. loncf embryo of Hepianchus cinereiis" . 

 By Prof. J. W. van Wuhe. 



(Communicated at the meeting of September 29, 1928). 



Many years ago I received this embryo frotn the Zoological Station 

 at Naples. It was tixed in sublimate and preserved in alcoliol. Just 

 as another specimen it was treated with methylene blue, in order 

 to make a skelet pre[)aration of it. 



This having proved quite successful with the one embryo, I decided 

 to preserve the other,, so as to make a series of cross sections later, 

 in order also to be able to examine the I'emaining organs. I intended 

 to wait with this until 1 had more of this rare material in different 

 stages. ! however received only one more embryo, 255 m.in. long, 

 which was simply treated with alcohol and was much too large 

 for making a series of sections. Here one would have to restrict 

 oneself to only a few parts. For this specimen I am again indebted 

 to the direction of the Station at Naples. 



When in theautumn of 1922 I had finished with the development 

 of the skeleton of Acanthias vulgaris ') 1 decided not to wait any 

 longer, and a series of cross sections of the 63 mm. long embryo 

 was made. The preservation proved to be excellent, notwithstanding 

 the previous long treatment of HCl alcohol necessary for the elimination 

 of the methylene blue from the remaining tissues, in order to restrict 

 the colour to the cartilage. The staining of the sections with ammonia- 

 carmine was also successful ; but the light blue tint of the cartilage 

 could not be intensified by the after-treatment with methylene blue 

 or victoria blue. The reason for this remained unknown to me. 



In the 255 m.m. long embryo, which had been in alcohol for 

 many years, the cartilage suffered itself to be stained deep blue. 



1) Van Wuhe, J. W. Friihe Entwicklungsstadien des Kopf- und Rumpfskeletts 

 von Acanthias vulgaris. Bijdragen tot de Dierkunde, publ. by the Kon. Zool. 

 Genootsch. Natura Artis Magistra at Amsterdam. Afl. 22, Feestnijmmer voor Max 

 WïBEH, 1922. 



