ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



655 



Pagan's Growing Slide.* — The Eev. A. Pagan's slide was designed 

 mainly for the purpose of watching the development of rotifers and other 

 organisms which require a constant change of water. Figs. 178-81 give the 

 essential points of its construction, which is very simple, and so far effective 

 as to have enahled Mr. Pagan to observe the growth of the spores of Volvox 

 globator after they had been confined to the slide for six weeks, the actual 

 process of germination taking three days to complete. 



Fig. 178 is a longitudinal vertical section of the whole apparatus drawn 

 to a scale of half the actual size. A is a wooden stand supporting a glass 



Fig. 178. 



trough B, from which a water supply is conveyed to a slide D by a siphon 

 C. This siphon is made from an ordinary capillary vaccine-tube, bent over 

 a minute gas-flame. The water is conveyed from the slide by means of a 

 spout F, made of blotting-paper, to another trough or suitable receptacle E. 

 Fig. 179 shows in full size an arrangement cut out of blotting-paper, and 

 placed on an ordinary slide, a being a circular hole for containing the object 

 under observation. This hole is connected by a narrow channel c with 

 another hole &, shaped as in the drawing, and so placed beneath the siphon c 

 as to receive a drop of water as it falls. It is sufficient, however, if the drop 



Fig. 179. 



falls on the blotting-paper. A third hole d serves to collect the super- 

 fluous water, and also acts as a reservoir when the slide is under examina- 

 tion with the Microscope, water being applied there from time to time with 

 a camel's-hair brush. 



When it is desired to use the instrument, the blotting-paper is wetted 

 and put on the slide, the drop of water containing the organism placed in 

 the hole a, and the whole is covered with thin glass up to the dotted line e, 



* Journ. Quek. Micr. Club, iii. (1887) pp. 81-3 (4 figs.)- 



