Structure and Polarity of Electric Motor Nerve-Cell in Torpedoes. 235 



were less and less. In the central parts of the specimen no osmotic action is 

 shown. The osmotic action produced by the alcohol has not moved the 

 nuclear organs with reference to one another. In the specimen in question 

 the plasmosome is clearly oriented with reference to the dorso-ventral line. 

 No matter from which side the nuclear content has been compressed, the 

 plasmosome is always clearly ventral in the compressed mass. 



Torpedo ocellata, No. 22, 30 cm. long (large), killed with a knife and the 

 entire brain fixed in Carnoy's fluid; absolute alcohol, chloroform, and glacial 

 acetic acid, equal parts, the fluid being saturated with corrosive sublimate. 

 This specimen showed about 85 per cent of its plasmosomes oriented ventrally, 

 the remaining 15 per cent being scattered in median or somewhat dorsal 

 positions. 



Torpedo ocellata, No. 28, 30 cm. long (large), killed with knife and brain 

 fixed in Carnoy's fluid; chloroform, absolute alcohol, and acetic acid, no 

 sublimate being added. A fair fixation with 90 per cent of the plasmosomes 

 ventrally oriented. 



Torpedo ocellata, No. 24, 11 cm. long (small). This small fish was thrown 

 whole into 60 per cent alcohol, containing 3.5 per cent of formol. It had 

 given many shocks before being killed. No orientation in a ventral direction 

 beyond a possible 5 per cent was found. 



Torpedo ocellata, No. 25, 38 cm. long (large) . This fish was left undisturbed 

 in a tank for 48 hours and then gently lifted out on a tray, where it remained 

 until dead. The brain was fixed in Bouin's fluid. 99 per cent of the plas- 

 mosomes were oriented sharply in a ventral direction. Chromosome bodies 

 were somewhat clumped, owing to the natural death of the fish, the karyosomes 

 standing out plainly and staining sharply and differently from the peri- 

 chromatin. 



Torpedo marmorata, No. 26, 16 cm. long (small). This fish was left undis- 

 turbed 48 hours and allowed to die on tray without discharging electricity. 

 About 5 per cent of ventral orientation of the plasmosome was found. 



Torpedo marmorata, No. 27, 11 cm. long (small). This small fish was 

 irritated until considerable electricity had been discharged and then the 

 brain-case was cut out while alive, the animal giving off strong shocks. After 

 cutting sections the electric motor nerve-cells showed barely 5 per cent of 

 ventral orientation, which appears to refute Magini's theory. 



Torpedo ocellata, No. 28, 16 cm. long (small). This fish rested undisturbed 

 for 48 hours and was allowed to die on tray. 10 per cent of ventral orientation. 



Torpedo ocellata, No. 29, 11 cm. long (small). Caused to discharge freely 

 and then killed by cutting out brain, with consequent strong shocks. No 

 perceptible orientation. 



Torpedo ocellata, No. 30, 40 cm. long (large). Kept for 48 hours at rest and 

 then gently lifted from the water on a board and allowed to die without giving 

 shocks. Brain fixed in Bouin's fluid. Sections in celloidin and paraffin show 

 over 95 per cent of ventral orientation. 



