ZOOLOGY AND BOTANY, MICROSCOPYj ETC. 



801 



attached a screw (R, fig. 140) for specially regulating the flame when it 

 has been reduced by the regulation apparatus. As the regulation of the 



Fig. 141. 



'^ppsi^ 



temperature is instantaneous, the vital conditions of bacteria at definite 

 temperatures can be studied exactly. 



Capillary Slide and accessories for the examination of Ova.* — 

 This apparatus, which was designed by M. L. Chabry for the examina- 

 tion of Ascidian ova, has now received several additions rendering it 

 more serviceable than the original form (see this Journal, 1887, p. 319). 



It consists of a thick glass plate p (fig. 142) placed on the stage of 

 the Microscope, and upon which rests a capillary tube T bent at a right 

 angle, the latter part projecting over the stage. The tube lies in a 

 couple of glass sockets d d fixed to the plate with shellac. This allows 

 the capillary tube to be pushed up and down from left to right, and also 

 to turn on its axis. This axial revolution is effected by a special con- 

 trivance. Po is a metal plate bent at a right angle with a long and a 

 short leg. The longer leg is clamped to the stage by a screw, so that 

 the shorter leg is parallel to the side of the stage and about 5 cm. distant 

 from it. Through the short leg passes the rod M B, bent twice at a right 

 angle, and one end of which is fixed on a disc, about the size of a penny 

 piece. K is a plate of shellac fastened to the short leg. By turning 

 the disc the capillary tube is made to revolve. The tubes must be per- 

 fectly free from air-bubbles, and it is advised to keep a quantity of 

 them on hand. They should be about 10 cm. long and arranged accord- 

 ing to the breadth of their lumen, and that tube should be selected of which 

 the diameter is about equal to that of the object to be examined, so that 

 when the tube is made to revolve the ova may not be damaged. 



The ova are introduced into the capillary tube by a suction-pump 

 made out of a piece of glass tubing fitted at both ends with a piece of 

 rubber tube. On one piece of the rubber tube is fitted a self-acting clamp, 

 between the clips of which is slipped the capillary tube. To the other 

 piece is fitted a small syringe, by the use of which the ova are sucked 



* Journ. de I'Anat. et de la Physiol., xxiii. (1887) pp. 167-320 (5 pis.). Cf. 

 Zeitschr. f. Wiss. Mikr., v. (1888) pp. 60-5 (2 figs.). 



