368 



SUMMABY OF CURRENT RESEARCHES RELATING TO 



is divided into ten chapters. Chapters i. and ii. (pp. 1-15) discuss 

 apparatus and the structure of colloids. Chapter iii. (pp. 16-25) deals 

 with the ultrainicroscopic examination of liquid colloids, specially 

 interesting to the biologist and the physician. Chapters iv. and v. 

 (pp. l'">— i s ) are occupied with blood, bacteria, and other such micro- 

 scopic objects. Chapter vi. (pp. 49-59) describes the author's own 

 researches on certain botanical objects (e.g. spirogyra. desmids, etc.). 

 Chapters vii. and viii. (pp. 60-67), plant cells, colloids, and textile 

 fibres. Chapter ix. (p. 73) is a summary ; and Chapter x. (pp. 74-83) is 

 bibliographical. 



The bibliography includes some 202 items. The plates include 

 some well-known objects (e.g. desmids, spermatozoids, etc.), as seen by 

 bright-ground and by dark-ground methods. The difference in appear- 

 ance is sometimes very remarkable. 



Micrometric Measurements by a Projected Scale.* — F. J. Clen- 

 dinnen gives the following description of the method devised by him. 



Fig. 48. 



The apparatus (fig. 48) consists of a wooden base 3 ft. in length and 

 8 in. wide, which carries the Microscope ; and a pair of steel rails, 2^ in. 

 apart, parallel with which is placed a scale graduated in centimetres and 

 millimetres. The tripod of the Microscope is fitted into slots on the 

 wooden base, so that its position is fixed while in use, but the Micro- 

 scope can be easily removed. The metal rails are projected forward 

 from the base of the tripod, and upon them runs an upright metal rod 

 carrying the screen, which may be lowered or raised by means of a 

 small set screw. Behind the screen, the rails also carry the lamp, which 

 may thus be adjusted to any requisite distance.. A micrometer of 

 known value being in position in the Microscope stage, the reticule upon 

 the screen may now be compared at various distances. These distances 

 being read off by means of the scale placed between the rails, the value 

 of the screen reticule becomes accurately known, and the stage micro- 

 meter may now be dispensed with, as it is used merely to determine an 

 exact calibration. 



* Trans- Australasian Med. Congress, 1903, ii. (1909) pp. 377-8 (1 pi.). 



