202 DIPS INTO MY AQUARIUM. 



determine the question. The beginning of this process is marked 

 by considerable changes in the colour and shape of the organism. 

 The bright green colour separates into distinct masses, divided 

 trom one another by colourless material. We then have the 

 appearance of a cell-wall containing a tiny green spherical centre 

 or nucleus. After an interval this green nucleus divides into a 

 number of smaller masses, which in due time escape out of the 

 ruptured cell-wall, and become independent individuals. The 

 difficulty of watching the life-history of these extraordinary objects 

 is increased by the fact that the tiny drop of water, in which alone 

 they can be properly studied under high powers, generally evapo- 

 rates before the cycle is completed. There is here, however, a 

 field worthy of further investigation, and as Euglence are easily 

 obtained from almost every ditch and stagnant pond, no disciple 

 of the microscope need be long without material for study. 



Besides Euglena viridis, there are several other species, all 

 very similar. E. spirogyra, or the sluggish Euglena, is usually 

 found alone and not in crowds. It is rather larger than E. viridis^ 

 and not so lively. There are tiny elevations or warts running 

 down the body in lines. When the body contracts, these protu- 

 berances present a spiral appearance, and it is this feature which 

 has originated its specific name. Another member of this group 

 is E. plenronecfes, which is like a tiny leaflet and is almost flat, the 

 upper side being very slightly convex. The tail is long, and is so 

 colourless that it is necessary to stain the water in order to see it 

 properly. It is almost as common as E. viridts, but does not 

 glide along quite so rapidly. Another species is called E. deses, 

 and is of solitary habits. None of these are very uncommon, 

 and all would repay thorough and systematic examination. 



(To be continued.) 



Differential Staining of Saccaromyces. — In order to 

 demonstrate the two membranes of the cell of the Fresh plant 

 and similar mycetic growths. Professor S. H. Vines first immerses 

 the growth in a solution of methyl violet, leaving until stained, 

 and, after washing in water, transfers to aniline green. The 

 staining does not in all cases take equally well, but many cells 

 will be found in which the outer membrane is stained green and 

 the inner violet. 



