554 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



actions of an amoeba or a maggot has put us in a fair way of appre- 

 ciating those of a man. If, therefore, better and clearer ideas of 

 animal existence can be fostered in young minds by the aid of any 

 optical appliance whatsoever, that appliance should be welcome as an 

 aid in practical objective instruction. No less effective is this instru- 

 ment in the illustration of many common facts in physical science. 

 The range of its apj)licability seems indeed to be limited only by the 

 resources, ingenuity, and ability of the lecturer." 



Nelson's Student's Microscope. — Fig. 94 shows a medium-sizo 

 Microscope, constructed by Messrs. Swift and Son, embodying some 



suggestions of Mr. E. M. Nelson 

 Fig. 94. with special reference to histo- 



logical research with high powers 

 where only a moderate outlay is 

 allowable. 



The principal point of novelty 

 is that the front of the stage is 

 cut away so that the position 

 of the substage, with the dia- 

 phragms, condenser, &c., may 

 be readily seen from above the 

 stage, and the diaphragms rapidly 

 changed ; also permitting the 

 finger to be placed on the upper 

 edge of the slide for safety in 

 focussing with high powers. 

 Amongst other additions it may 

 be noted that finders are applied 

 to the stage by which the posi- 

 tion of an object may be recorded 

 without the use of mechanical 

 movements, the graduations for 

 the vertical movement being on 

 the stage plate, and those for the 

 lateral movement on the sliding 

 bar carrying the object. The 

 optical body divides in two for 

 portability. The eye-pieces are 

 fitted with different lengths of 

 tubing, so that the 10-inch length 

 is maintained with each from 

 the diaphragm to the nose-piece, 

 as with Powell and Lealand's 

 Microscopes. Mr. Nelson's centering substage with lateral swinging 

 diaphragm-carrier is also applied (for description and fig. see Vol. I., 

 1881, pp. 125-6). 



Watson's Portable Swinging Mirror and Substage Microscope.— 

 We have always considered Bulloch's Biological Microscope (Vol. III., 

 1880, p. 1078) to be one of the handiest and most practical forms of 



