ABSTRACT AND REVIEW. 107 



in culture. They lie embedded in the threads (visible after 

 treatment with any reagent, and probably present though un- 

 detectable in the living state) of the hyaloplasma, which 

 themselves are coiled in a scarcely staining mass (Kupfer's 

 paraplasma), the kyanophilous physodes being immediately 

 surrounded by an erythrophilous layer. This can be readily 

 made out with iodine, which stains this layer deeply, the 

 physode itself not at all. 



The hyaloplasmic threads are closely packed round the nuclei, 

 less so round the chromatophores ; aggregations of them, with 

 their contained physodes, are especially common in places 

 where the cell membrane is undergoing a marked growth, 

 which would suggest that the physodes are reserve food 

 material, the nature of which cannot, however, be at present 

 more precisely affirmed. The hyaloplasmic threads never 

 branch or anastomose. 



e. The Crystals. — These are found, in " Brownian " move- 

 ment, in the vacuoles. They are generally egested by the 

 organism when it assumes the amoeboid stage, and are some- 

 times left behind in the cyst. That they are crystalline is 

 proved by polarisation, and that they are of calcium oxalate is 

 proved by their insolubility in acetic acid, whereas they readily 

 dissolve, even in weak solutions of hydrochloric, sulphuric, 

 and nitric acids, without the evolution of bubbles. If strong 

 sulphuric acid is used crystals of calcium sulphate are formed, 

 and finally, if they be heated, the calcium oxalate is converted 

 into what is probably calcium oxide, which is then soluble in 

 acetic acid. 



The form of the single crystal is rod-shaped ; when cut it is 

 to be supposed that they are mono-symmetric ; double and 

 triple crystals also occur, as well as aggregations, which stick 

 together and may completely fill up a vacuole. These crystals 

 are never found in the hyaloplasmic threads, and therefore 

 probably arise in the paraplasma, or may possibly be sometimes 

 formed in the vacuoles themselves. 



/. The Cell-wall. — This gives the characteristic cellulose 

 reaction of blue or dark violet with iodine and sulphuric acid. 



