l893-] NEW-YORK MICROSCOPICAL SOCIETY. 105 



of the bright sunlight for a quarter of an hour or longer. When 

 the rays of the sun had acted sufficiently upon and had thor- 

 oughly dried the diatoms, the next step was to recover them by 

 washing the material in pure water and collecting the residuum 

 together again. The experiment proved successful, and the 

 diatoms were seen to be duly stained a beautiful light shade of 

 blue. 



I next mounted a slide in balsam and viewed it under the 

 microscope, and was well pleased with the result. The internal 

 corrugations held the stain, differentiating the various markings 

 in a moderately satisfactory manner, and gave the frustules a 

 far better appearance than when unstained. But, not being fully 

 satisfied with the effects of the blue stain, it occurred to me to 

 restain a portion of the material already stained blue. Before 

 having accomplished the blue staining I feared that it would be 

 a failure, and thought to substitute aniline violet for the blue 

 liquid. Taking a pipette, I deposited a quantity of aniline into 

 the blue liquid containing the diatoms, when I observed that the 

 liquids would not mix, but the aniline at once gathered in round 

 drops. Failing in this, I drew off all the blue staining fluid 

 from the diatoms and removed the moisture by decanting again 

 on blotting paper. I next put the diatomaceous mass into pure 

 aniline, and allowed it to be immersed for about five minutes or 

 more. I then removed the excess of aniline dye, and washed the 

 diatoms in repeated changes of pure water until no more stain 

 came off in the water. I then dried the stained material and 

 mounted a slide in balsam. When I submitted the violet-stained 

 diatom slide to microscopic inspection I was pleased at my suc- 

 cess, as there was in many frustules a perfect differentiation of 

 all markings of every character; the punctate striae o{ Cymde/ia, the 

 pinnulse of all the Pi?inulari(B, and the ribs of Surirella, were, in 

 many cases, so perfect that every individual rib could be easily 

 counted, the markings called canaliculi, or costge, having the 

 appearance of a dark, short line with distinct semicircular ends, 

 each perfectly differentiated from its neighboring rib by a deli- 

 cate, clear line of silex showing no stain ; nor was the median 

 smooth surface, divided by the raphe, stained, but the lines of the 

 raphe and its terminal dots were filled with color. 



I offer this as my view of the staining : The internal chemi- 



