ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
107 
are therefore somewhat hard to see. Moreover the segment is too small, 
and the division lines therefore too close ; and one has to bring oue’s 
head almost to the horizontal plane of the table. These inconveniences 
are remedied by the application of a different and larger segment. The 
Fm. 23. 
divided surface of the new segment is placed vertically, and is 1J times 
greater than before. Instead of on a shining metallic surface, the 
division lines are now marked in black on a white celluloid strip. 
(3) A knife-carrier rotatory about a vertical axis . — The original in- 
