224 



THE AMEKICAN MONTHLY 



[December, 



On the Processes of Coloring 



Living Microscopic 



Organisms. 



BY A. CERTES.* 



In describing before the Society 

 the processes of coloring living tis- 

 sues by cyanine or quinoline blue, 

 or Bismarck brown, I remarked that 

 the nucleus of infusoria seemed not 

 to be colored by the reagent so long 

 as the animals continued to live, and 

 even for several hours after death. 

 Nothing has occurred to contradict 

 the first observations. I have only 

 found that the cyanine colors the 

 living tissues even when the amount 

 in solution does not exceed one five 

 hundred thousandth part (rinrcroTr). 



Dr. Henneguy having informed me 

 of the analagous properties of a me- 

 thyl violet known as dahlia, I have 

 pursued these experiments with dif- 

 ferent violets of Paris, and I have 

 found that, despite their very similar 

 chemical composition, their action 

 varies according to the kind and also 

 to the trade-mark. Some are always 

 poisonous to all species of infusoria. 

 Others only color certain species 

 among those that live in the same 

 liquid. Others finally, — and it is to 

 this point that I call attention of the 

 Society — color the nucleus of the 

 living infusorium and color it more 

 strongly than the protoplasm. 



In general, with the violets of Paris 

 the cilia are always stained, and the 

 liquid of the contractile vacuole — so 

 far as one can judge in an observa- 

 tion of such a delicate nature — often 

 participates in the general coloration. 



As concerns the nucleus, I have as- 

 certained in a most evident manner 

 the selection of the coloring matter, 

 by it, first with the violet B B B B B. 

 upon the large Balantidimn from the 

 intestine of a Bonibinator tgnezis, and 

 in other species f with the violet 

 B B B B B and dahlia violet. The 



* Translated for this Journal from the 

 Bulletin de la SociJt/ Zool. de France. 



■j- Paramecium aurelia, Vorticellas, Oxytri- 

 ches, Stylonychia, Volvox globator 



violet 50 N, and the gentian violet, 

 on the contrary, notwithstanding their 

 great power of coloring, have no ten- 

 dency to go to the nucleus. 



As to the more or less great resist- 

 ance that certain closely allied spe- 

 cies oppose to the action of the same 

 reagent, I will cite the fact, in sup- 

 port of my observation, that I have 

 seen in the same liquid, small species 

 of Paramecia * continue to live in- 

 definitely without being colored, while 

 all the others of equal or greater size 

 had entirely disappeared. 



The coloration of the nucleus of 

 the infusoria is a new fact. It is so 

 much the more interesting to ascer- 

 tain that the more recent researches 

 demonstrate the preponderating role 

 which this element plays in the phe- 

 nomena of nutrition and reproduc- 

 tion, and, if one may also so speak, in 

 the government of the life of unicel- 

 lular organisms. 



The Podura Scale. 



BY THE EDITOR. 



The scales of the insect, long 

 known by the name of Podiira, have 

 been renowned as test-objects for 

 many years. They are not test- 

 objects in the sense of being difficult 

 to resolve, for, as Dr. Carpenter has 

 said, a good 2-inch objective will 

 show their markings ; yet they are 

 valuable for testing objectives of all 

 powers up to a twentieth or fiftieth. 

 The podura-scale has been the sub- 

 ject of much study by microscopists 

 in the past, and eminent authorities 

 have differed very much in their in- 

 terpretations of the microscopic ap- 

 pearance of the scale, which, under 

 different conditions of illumination, 

 could be greatly changed. Dr. Roys- 

 ton-Piggott described a beaded ap- 

 pearance, which he deemed to be the 

 true structure. Mr. R. Beck main- 

 tained that the proper microscopic ap- 

 pearance was that of rows of exclama- 

 tion points. Without further allusion 



* Probably Paramecium pectinum. 



