( 814 ) 



here, too, the resistance increases with heating, decreases with 

 exposure to light : ). 



In conjunction with Mr. Vas Nunes I hope shortly to publish also 

 some quantitative data on the phenomenon discovered by me, and 

 also on the behaviour of the melted and again solidified antimonite 

 and the analogous selenium compound. This investigation has been 

 made in the Physical Laboratory at Amsterdam. 



Anatomy. — "On the influence of the fins upon the form of the 

 trimk-myotome" . By B. van Tricht. (Communicated by Prof. 

 G. C. .1. Vosmaek). (From the Anatomical Institute at Leyden). 



(Communicated in the meeting of March 30, 1907). 



This research forms a direct sequel to Professor Langelaan's work 

 "On the Form of the Trunk-myotome", and is intended to show the 

 influence of the fins upon the form of the myotome. The method 

 which I followed, was based upon the chief result of the foregoing 

 research viz. that the differentiation of the myotome takes place in 

 a continuous manner by means of folding, and that it is possible to 

 follow the process of folding in dissecting the intermyotomal tissue. 

 Now the method of direct dissection proved to be restricted in its 

 application, so that it was necessary partly to apply a more indirect 

 one. This latter method rests upon the relation, which exists between 

 the form of the myotome and the structure of the transverse sections 

 of the animal. 



Differentiation of the dorsal musculature. 



From a rather large sample of Mustelus vulgaris the skin with 

 the underlying connective tissue was removed, so that the external 

 surface of the myotoms was laid bare (figure I). Then in the region 

 before the first dorsal fin the parts constituting one and the same 

 myotome were determined ; the form of this myotome exhibited 

 about the same form as in Acanthias, only the lateral part of 

 the myotome proved to be displaced caudally ; the breadth of 

 this displacement amounted to about half the breadth of the myo- 

 tome. This myotome was arbitrarily indicated by the number 



l ) I have made an arrangement with Mr. J. W. Giltay at Delft with regard to 

 the mounting of antimonite preparations, and the preparation of antimonite cells 

 for practical use. 



