1893.] MICROSCOPICAL JOURNAL. 18Y 



Infusoria, within the five pouches of the stomach of the Echin- 

 oderms, in the segmental organs of the leeches, of the Oligo- 

 chaeta and of the Polychaeta. 



Griffiths of Edinburgh, has demonstrated the presence of 

 murexide in the contractile vesicles of Amoeba, of Paramecium 

 and of Vorticella. The process is to place a number of the ani- 

 mals on a slide and to cover as usual. They are then killed by 

 alcohol, which is to be followed by nitric acid. The slide is 

 gently warmed and ammonia introduced, when, if the experiment 

 succeeds, the purple, prismatic crystals of murexide will make 

 their appearance in the contractile vesicle, showing that uric 

 acid had been present there. I do not think that a gas could 

 hold uric acid in solution any more easily than it could be 

 stained. 



"Through all the multitudinous changes " says Griffiths 

 ''that have taken place during the lapse of ages, in the develop- 

 ment of the mammalian kidney, we find that the physiological 

 functions are the same as occur in its original or primitive form 

 as represented in the Protozoa. It is not going too far to say, 

 that within these lower forms of animal life we have all the 

 necessary mechanism for the creatures to breathe, digest and 

 excrete. The only difference is that in the Protozoa the cell 

 performs numerous functions, whereas in the Vertebrata these 

 functions are localized in special organs." And Huxley says, 

 " * * * * the vertebrate kidney is an extreme m edification of 

 an organ, the primitive type of which is to be found in the or 

 gan of Bojanusofthe Mollusk, and in the segmental organ of the 

 Annelid ; and, to go still lower, in the water- vascular sj'S- 

 tem of the Turbellarian. And this, in its lowest form, is so 

 similar to the more complex conditions of the contractile 

 yacuoleofa Protozoon, that it is hardly straining analogy too 

 far to regard the latter as the primary form of uropoetic as well 

 as of internal respiratory apparatus." 



Man\' theories have been propounded as to the final disposal 

 of the watery contents of the vesicles. Those that think the 

 contents are a gas, as Dr. Albert Schneider (Amer. Mo. Micro. 

 Journal, March, 189B), is fully convinced that they are and that 

 this gas is forced into the general system by the pulsations of 

 the organ, would do well to study the optical action of a gas- 

 bubble and of a drop of liquid enclosed within the endoplasm 



