556 SUMMARY OF CUTIRENT RESEARCHES RELATINQ TO 



ing the uuclons, which, in living infusoria, is not coloured by quino- 

 lein-blue or Bismarck-brown. 



Very weak aqueous solutions of dahlia, acid-grocn, and malachite- 

 green colour the nucleus of a large number of ciliate and flagellate 

 Infusoria. Diphcnylamine-blue, on the contrary, even in solution 

 of a deep hue, has no toxic action on Infusoria, which live and 

 develope in it without any coloration being produced, except in the 

 stomachal vacuoles from the ingestion of coloured food. 



The solutions of dahlia, acid-green, and malachite-green should be 

 made with the water in which the organisms to be studied are living. 

 The resistance to the toxic action of the staining reagents is not the 

 same in every species. M. Certes has succeeded with solutions of 

 1/10,000 as a maximum, and 1/100,000 as a minimum. . 



With dahlia and malachite-green the nucleus behaves differently 

 in species which are closely connected, and in the same species the 

 division of the chromatic material, or the affinity of the nucleus for 

 colouring matters vary according as the infusoria are more or less 

 distant from a period of reproduction by conjugation, e. g. malachite 

 green colours intensely the double nuclei of Siijhmjchia inytihs, 

 various Oxytriehes, &c., while the simple nucleus of Paramoncium 

 aiircJia is more faintly stained. 



With dahlia, the coloration, more intense in the nticleus, extends, 

 but more faintly, to the rest of the parenchyma. There is often a 

 more coloured zone at the anterior part of the animal, and the sarcodo 

 expansions, formed of glycogen, take a feeble tint, which does not 

 seem to occur in Infusoria treated by other colouring materials. 



The stomachal vacuoles are always strongly coloured whatever the 

 reagent employed, owing to the vegetable matter or dead animals 

 which are ingested. If a living infusorian is swallowed by a carni- 

 vorous infusorian, it only becomes intensely coloured when it has been 

 killed by the action of the gastric juices. 



Even deeply coloured solutions of diphenylamine-blue and the 

 blues of Poirrier (B B S E and C 3 B) have no toxic action on Infu- 

 soria, while they colour and rapidly kill a number of bacteria. 



The contractile vacuole is never coloured, except perhaps by 

 dahlia, which faintly stains the sarcode expansions. 

 » Dahlia, acid-green, and malachite-green, &c., bring about in most 

 species slowing of their movements from a kind of paralysis. The 

 contractions of the contractile vacuole first become less frequent, and 

 this morbid phenomenon seems to explain the dropsy which ensues 

 before death. 



M. Certes noticed some peculiar phenomena in some Stentors 

 which had been living for several days in a solution of Poirrier blue. 

 The accumulation of the liquid had transformed the individuals into 

 a large soapy bulla, the wall of which contained the nuclei and buccal 

 ciliary apparatus. At a given moment, one of the individuals began 

 to open, and rejected the enormous vacuole inclosed in a special wall 

 and almost as large as itself. It then closed up and swam about 

 apparently unhurt, while the vacuole remained inert at the spot 

 where it was rejected, and became coloured blue. 



