Voi.xxvii.j Hardy, A Red Euglena. 217 



described as having green colour filling the cell, excepting the 

 anterior end and the tail-like posterior, which are hyaline. In 

 E. rubra the red colour (erythrin ?) that pervades aU parts of 

 the cell, excepting the posterior end (where the tip may be 

 hyaline or sometimes about .1 of the organism's length green) 

 is usually dense to the anterior extremity — very rarely a trace 

 of green — so that the eye-speck, of same hue, was difficult to 

 distinguish. 



Under a magnification of about 1,500 diameters (Leitz's 

 oil immersion and Watson's E eye-piece with Abbe condenser), 

 the red specks which gave the colour to the living organism 

 appeared to be constantly forming by the aggregation of still 

 more minute particles, which seemed to be attracted by a 

 centripetal force until the compound particle had reached a 

 certain size, while other particles appeared to break up or dis- 

 solve away. I can offer no explanation of this, unless it is 

 part of the process of resorption. I did not observe any 

 chromatophores, such as described by Miss Sallitt or Professor 

 Bower. 



When red organisms of this species encysted, any green 

 colour present took up a peripheral position, and if preserved 

 alive the green soon disappeared, leaving only the red cysts 

 previously described. The red particles seemed to be con- 

 tained in globules of oil, having an appearance something like 

 that of fig. 3 of the accompanying plate — globules which 

 crowded the cell from end to end. Specimens mounted in 

 formalin had in a few years lost most of their pristine colour, nor 

 could I observe the globules already noticed ; but most cells 

 were crowded from stem to stern with grains (paramylon ?) 

 measuring up to 6 ;^. x 4.5 /7., and which showed no reaction 

 to iodine, iodine and sulphuric acid, or chlor-zinc- iodine. 

 No red particles were then visible. Instead, a red-coloured 

 oil partly suffused the cells, and formed a film which 

 coated the grains more or less, as shown in fig. 4. In another 

 mount (the medium being in doubt, but probably formalin), 

 some red oil, extruded from a cell, formed in globules 

 of varying sizes (and of colour similar to the red " No. i " of 

 the type colour-chart under " Spectrum " in the Standard 

 Dictionary), and I was surprised to find these exhibiting 

 Brownian movement, the smallest vibrating more rapidly than 

 the larger, but all of slower movement than the solid particles 

 in vacuoles of Closteria and Pleurotenia. My limited literature 

 on the subject gives me no information of Brownian move- 

 ment of oil globules in liquids of different densities, and, for 

 all I know to the contrary, this may be a novelty. 



When equal quantities of E. rubra and E. viridis were kept 

 separately in shahow dishes and in specimen tubes, it was 



