82 T. S. SMITHSON ON A NEW ARRANGEMENT OF GROWING SLIDE. 



confined to the slide for six weeks, the actual process of 

 germination taking three days to complete. 



Fig. 1 is a longitudinal vertical section of the whole ap- 

 paratus drawn to a scale of half the actual size ; A is a 

 wooden stand supporting a glass 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 conve} r ed from the slide by 

 means of a spout (F), made of blotting-paper, to another trough 

 or suitable receptacle (E). 



Fig. 2 shows in full size an arrangement cut out of blotting- 

 paper and placed on an ordinary slide; a is a circular hole for 

 containing the object under observation. This hole is con- 

 nected by a narrow channel (c) with another hole (ft), 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 

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

 the superfluous w r ater, and also acts as a reservoir when the 

 slide is under examination 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,. three f-in. square cover 

 glasses being very suitable for this purpose. The siphon may 

 now be started, the current being regulated to about one drop 

 per minute by means of ;i linen thread, unravelled, soaked in 

 water t<> gel rid of air bubbles, and pushed up the shorter limb 

 of tlic siphon. The water is drawn off at the other end of the 

 Blide by three strips of blotting-paper (shown detached at Fig. 

 3). one 1)i«»;k1 and the other two less than half the width placed 

 under the broad slip, thus forming a kind of channel for the 

 water to flow fchronerh. 



After a time the blotting-paper is liable to get clogged, and 

 will not allow the water to filter through ; it must therefore be 

 changed. To enable lliis to be done, the part used on the slide 

 is out in pieces in the manner indicated in Fig. 2. 



The form of the lid of the trongh V> is shown in Fig. 4 j it 

 is provided with three holes drilled one inch apart, in order 



