244 SUMMARY OF CURRENT RESEARCHES RELATING TO 



centre to the same extent. The disk also acts as a guide to the rollers, 

 and thus controls the movement of the table. 



Standing on the clockwork behind the turntable, and parallel to the 

 front, is a sliding-bar carrying a pointer that can be adjusted to any 

 required position. This pointer acts as a guide for the brush, and the 

 distance the point is placed from the long axis of the oval determines 

 the width of the oval. It is necessary to place the guide for the brush 

 opposite the point at the long axis. An arm-rest is placed in position 

 for the brush-hand. 



By the use of this instrument it is possible to run round a needle 

 point or strike a straight line, besides making circles and ellipses. A 

 diamond may be attached to the pointer for cutting cover-glasses. 



To set the apparatus to turn any oval : — (1) Let the end of the 

 pointer rest over the centre of the table when it is in mid-position ; 

 (2) turn the table half round so that a glass slip is end-on to the 

 operator ; then (3) shift the pointer to the right until it is over the 

 end of the short axis of the oval ; (4) turn the table back to its original 

 position ; (5) decentre the disk on table, moving it to the left by 

 means of the long set-screws until the pointer is over the end of the 

 long axis of the oval. 



Mounting Diatoms.*— H. v. Schonfeldt has used syndeticon (the 

 best Norwegian isinglass) with gratifying results. The medium is com- 

 posed of acetic acid (64 p.c.) 25 grm., syndeticon 4 grm., absolute alcohol 

 5 grm., isobutyl-alcohol 3 grm. The isinglass is first mixed with 

 the acetic acid and the other ingredients added afterwards gradually. 

 The mixture is then filtered. With a glass rod drawn to a fine point a 

 minute drop of the fluid is deposited on a perfectly clean cover-glass, on 

 which it at once forms a perfectly transparent layer. After the diatoms 

 are oriented it is merely necessary to breathe on the surface of the film. 

 This firmly fixes the Diatoms, and the rest of the procedure is well 

 known. 



(6) Miscellaneous.' 



Measurement of Trypanosomes.f — A. Lingard has adopted the 

 following system for measuring Trypanosomes for a number of years. 

 The fixed points selected between which measurements have been 

 carried out are the following (fig. 87) : — 



1. Between the posterior extremity of the parasite and the centre of 

 the blepharoplast. 



2. The centre of the blepharoplast to a point corresponding with 

 the posterior edge of the nutritive nucleus. 



3. From the posterior to the anterior edge of the nutritive nucleus. 



4. From the anterior edge of nucleus to the anterior end of the 

 body. 



5. The length of the free flagellum. 



6. The maximum width of the body. 



* Zeitschr. angw. Mikrosk., xii. (1906) pp. 247-50. 

 t Journ. Tropical Vet. Sci., i. (1906) pp. 5-14 (1 pi.). 



