3i8 THE POPULAR SCIENCE MONTHLY. 



tonic spasm of the same kind as that already alluded to in the case of 

 Tiaropsis polydiademata. Now, it is a remarkable fact that into what- 

 ever form the bell of this medusa is cut — saj, for instance, into the 

 form of a long ribbon — whenever a locomotor contraction is started by 

 stimulating an^- part of the general nervo-muscular sheet, it will pass 

 all through that sheet, from end to end of the ribbon, in the form of an 

 ordinary or gentle contractile wave. On the other hand, whenever a 

 spasmodic contraction is started in the nervo-muscular sheet by stimu- 

 lating any of the marginal ganglia, it will pass all through that sheet, 

 from end to end of the ribbon, in the form of a spasmodic or violent 

 contractile wave. Hence the muscular fibres of this medusa are capa- 

 ble of liberating this energy in either of two very different ways ; and 

 whenever some of them liberate their energy in one of these two ways, 

 they determine that all the other fibres in the nervo-muscular sheet 

 shall do the same. So that we may adopt a far-fetched but convenient 

 simile, and liken the muscular fibres in this medusa to the fibres in a 

 mass of gun-cotton. For in a mass of gun-cotton the fibres are like- 

 wise able to liberate their energy in either of two very different ways 

 — viz., either by burning in quiet flame when they are simply ignited, 

 or by exploding in a violent manner when they are detonated, as by a 

 percussion-cap. And both in the case of the muscle-fibres of Stauro- 

 phora and the cotton-fibres of gun-cotton, whenever any one of the 

 whole number is made by appropriate stimulation (i. e., muscular stim- 

 ulation or ignition) to liberate its energy in a quiet manner, then all 

 the other fibres in the mass do the same ; whereas, if any one of the 

 whole number is made by another appropriate stimulation (i. e., gan- 

 glionic stimulation or detonation) to liberate its energy in a violent 

 manner, then all the other fibres in the mass do the same. Now why 

 the ganglia of this medusa should thus act as detonators to the muscu- 

 lar fibres, and why, if they do, the muscular fibres should be capable of 

 two such different kinds of response — these are questions quite novel 

 in physiology, and as such I will not endeavor to answer them. 



Poisons. — As my space is now very nearly exhausted, I will con- 

 clude this article by very briefly stating the general results of a large 

 number of observations concerning the action of various nerve-poisons 

 on the Medxisoe. It is easy to see that this is an important branch of 

 the inquiry on which I am engaged ; for in the nerve-poisons we have, 

 as it were, so many tests whereby to ascertain whether nerve-tissue, 

 where it first appears u2Don the scene of life, is of the same essential 

 character, as to its various functions, as is the nerve-tissue of higher 

 animals. 



Chloroform, ether, morphia, etc., all exert their anaesthesiating influ- 

 ence on the Medusce quite as decidedly as they do on the higher ani- 

 mals. Soon after a few drops of the aneesthetic have been added to the 

 water in which the Medusm are contained, the swimming motions of the 

 latter become progressively slower and feebler, until in a minute or two 



