SEA MUSSEL MYTILUS EDULIS. 23 I 



there was some injurious compound present in the water which was taken up by the 

 mussel and stored in the liver. 



To test this, Thesen (1902) placed some mussels in weak solutions of strychnine, 

 curare, and the poison of mussels. He was confident that at the end of a certain time 

 these poisons were taken up by the liver. Schmidtmann's (1888) evidence supports 

 this view. He observed that harmless mussels placed in the suspected Wilhelmshaven 

 basin became more toxic the longer they remained there. After 24 hours they developed 

 sufficient poison to kill a rabbit in 1 ]/i hours, after 48 hours in 1 2 minutes, after 72 hours 

 in 4>2 minutes, and after 96 hours in from 2 to 4 minutes. Mussels which were capable 

 of killing rabbits in a few minutes, after being placed in the open water of the sea for a 

 period of 8 hours, were unable to cause the death of rabbits in less than i>2 hours. But all 

 efforts to isolate the mussel poison in a preformed condition from the stagnant water met 

 with negative results. 



Lindner (1888) assumed that the poison was produced by certain Protozoa which he 

 found present in considerable numbers in the toxic mussels. Popular opinion has 

 attributed the production of the poison to various sources. Some think it is due to the 

 absorption of copper salts which come from the metal sheaths of ships; others believe 

 that it comes from the eggs of starfish which are consumed by the mollusk. This view 

 is evidently without foundation, for there is apparently no authentic record of starfish 

 eggs being poisonous or ever being found in the mussel. It has also been assumed 

 without reason that the poison comes from the little crab, Pinnotheres maculatum, 

 which lives in the mantle cavity. It has also been accredited to the byssus. 



The most plausible explanation of the origin of the poison is contributed by Lustig 

 (1888), who studied the subject from the bacteriological standpoint. He obtained 

 some mussels from Genoa and Trieste which exhibited all the physical characters of the 

 poisonous variety. A sample of them which was fed to a cat and a rabbit produced 

 vomiting which was followed by death in less than 24 hours, accompanied with the char- 

 acteristic anatomical features of enteritis. From the livers of these mussels he obtained, 

 by Koch's method, cultures of two microorganisms, one of which proved to be pathogenic. 

 The latter organism is a straight, slender bacillus varying from 0.8 to 1.0 micron in length. 

 It stains with gentian violet, fuchsin, methyl violet, and Grams method. In old cultures 

 the bacilli unite into a spiral form. They liquefy gelatin. Twenty-four hours after 

 infection they produce rather large colonies, having a funnel form with a dense 

 whitish mass at the center similar to that of the bacillus of Finkler and Prior. 



Test-tube inoculations show a bubble of gas on the surface of the gelatin at the end 

 of 12 hours, and at the end of 24 hours the gelatin at this point is liquefied into the funnel 

 form. The depression continues to deepen by liquefaction, until at the end of 8 hours 

 more all the gelatin is dissolved into a cloudy, grayish liquid, on the surface of which there 

 is a delicate green ring. The cultures give off a nauseating odor. The bacillus grows 

 readily on agar-agar at a temperature of 16 to 20 C. and on potatoes at ordinary room 

 temperature. The potato culture takes the form of a yellow film. It also develops well 

 in sterilized milk or bouillon. 



To show the relation of this organism to the Mytilus poison, Lustig performed a 

 series of feeding experiments and of injections on rabbits and guinea pigs. From some 

 24-hour gelatin cultures he transferred by means of a sterilized platinum needle about 

 4 to 6 drops to small cubes of sterilized potato which were preserved in sterilized glass 



