284 THE MICROSCOPE 



" Did we trust solely to the eye, we should indeed be 

 very liable to pronounce these variable and beautiful forms 

 as belonging to animals rather than vegetables. All 

 favours this supposition. Their symmetrical division into 

 parts; the exquisite disc-form, finely cut and toothed 

 Micrasterias ; the lobed Euastrum; the Cosmarium, glit- 

 tering as it were with gems ; the Xanlhidium, armed with 

 spines ; the scimitar-shaped Closterium, embellished with 

 striae ; the Desmidium, resembling a tape- worm ; and the 

 strangely insect-like Staurastrum, sometimes furnished 

 with arms, as if for the purpose of seizing its prey ; all 

 these characteristics appear to a superficial observer to 

 belong rather to the lowest forms of animal, than vege- 

 table life." Another indication Dr. Bailey adduced, by 

 rendering apparent their power of motion; taking a por- 

 tion of mud covered with Closteria, and placing it in 

 water exposed to light ; after a time, it will be seen tha* 

 if the Closteria are buried in the mud, they work their 

 way to the surface, and cover it with a green stratum : 

 this is no doubt owing to the stimulus light exerts upon 

 all matter, although at first appearing very like a volun- 

 tary effort. Another is afforded by their retiring beneath 

 the surface when the pools dry up. Mr. Ealfs states that 

 he has taken advantage of this circumstance to obtain 

 specimens less mingled with foreign matter than they 

 would otherwise have been. 



During the summmer of 1854 the Eev. Lord S. G. 

 Osborne drew my attention to the economy of an interest- 

 ing specimen of this family, the Closterium Lunula; after 

 many careful investigations he came to the conclusion 

 that the membrane of the endochrome, both on its inner 

 and outer surface, is ciliated. 



In the Closterium Lunula, we have ascertained that the 

 best view of its circulation is obtained by the use of 

 strong daylight, or sunlight transmitted through coloured 

 glass, or such a combination of tinted glass as that 



be seen in the interior of the cell, starch cannot be present. A small quantity ct 

 diluted tincture of iodine may be applied, removing the free iodine by the aid of 

 beat, occasionally adding a little water to facilitate its removal. This also will 

 assist in the removal of the brownish stain which at first obscures the charac- 

 teristic purple tint ; and then, by applying the highest power of the microscope, 

 the peculiar colour of the purple iodide of starch will in general be perceived. 



