for the Microscope. 6? 



486. RALFS'S ZYGNEMA (Zygnema Ralfsit). The fila- 

 ments jointed ; cells three or four times as long as broad ; 

 contents green, collected in the form of dumb-bells. 

 Standing water on commons. (PI. VI, fig. 22.) 



487. The VOLVOX (Volvox globator) is common 

 enough in most pools, and consists of a ciliated reticu- 

 lated sphere, generally enclosing miniature spheres of a 

 like character, of a deep green colour, themselves young 

 stages of the same plant. The rolling movement of these 

 spheres, when living, and the bright colour cannot, of 

 course, be preserved in mounting; hence the Volvox 

 should be examined alive. 



488. The PANDORINA (Pandorina moruni) is a less 

 beautiful object, but not less interesting. A number of 

 little green bodies, with long cilia, are associated together 

 in a cluster, and thus they move about in the water. They 

 occur in pools amongst duckweed and Conferva, and are 

 not uncommon. 



489. The BREASTPLATE (Gonhim pedorale). Near the 

 surface in clear water. Square, with about sixteen green 

 cells, each with a pair of cilia. 



490. GREEN PROTOCOCCUS (Protococcus viridis). The 

 plant consists of a single cell, first developed on moist 

 earth, and then moving about in standing water, as zoo- 

 spores. At some periods of rest, the colour is reddish. 



SECTION II. ANIMAL. 



491. PLUMULES OF SMALL WHITE BUTTERFLY (Pieris 

 jRapa}. Plumules are characteristic scales found on the 

 upper surface of the fore wings of male butterflies. 

 These are expanded below, with a broad deep notch, 

 and tufted at the apex. (PI. VII., fig. 7.) 



492. PLUMULES OF ORANGE TIP (Pieris cardamines). 

 Fan-shaped, with the sides nearly parallel, and the ends 

 slightly convex and fringed. 



