196 



THE MICROSCOPE. 



and animal life pass through ; a patient investigation 

 will probably show that many which are now classed 

 as distinct species are merely different phases of the 

 same type, which alternate according to the varied 



Fro. 135. Holman's Life Slide. Full size. 



conditions of temperature and nutrition under which 

 they are placed. 



Holman's life slide consists of a 3 x 1 inch glass 

 slide, with a deep oval cavity in the middle to receive 

 the material for observation. A shallow oval is ground 

 and polished around the deep cavity, forming a bevel. 



FIG. 136. Holman's Moist Chamber. 



From this bevel a fine cut extends, to furnish fresh air 

 to the living low forms of life which invariably seek 

 the bevelled edge of the cavity, thus bringing them 

 within the reach of the highest powers. 



Mr. Holman contrived a form of " moist chamber,'' 



