ADULTERATION OF COFFEE. 115 



it is quite possible to do, but there are a few species the ova of 

 which do certainly lose some of their living colour, the most 

 notable being Pandalus annidicornis^ whose eggs are of a remark- 

 able turquoise blue. This colour it is at present impossible, 

 under preservation, to retain. 



The method of examination best adapted to these objects, in 

 order to define their structure and make out their general form, is 

 by means of the Binocular Microscope with a ij-in. or 2-in, 

 object glass, No. i eye-piece, and either parabola or spot-lens ; if, 

 however, the ova be small, or it is desired to examine more 

 minutely the structure of any part, a higher power with different 

 illumination may be resorted to. If, after suitable preparation, 

 they be thus examined, they will be found not only to have 

 retained their rotundity and natural appearance, but it will be 

 quite easy to discern the limbs, pigment cells, tail appendages, 

 etc., of the mature Zooea, though still enclosed in the egg-envelope. 



Voz Hbiilteration of Coffee anb tbe 

 flDicro6COpe* 



By J. S. Harrison, F.R.M.S. 



Plate II. 



IN the small town in which I reside, I happen to know the 

 possessors of several microscopes, who do not put their 

 instruments to any practical use, and I have no doubt such is 

 the case also in many other parts of the country ; so that a large 

 amount of microscopic power lies dormant, merely for the want of 

 knowing what to do with it. In the hope, therefore, of par- 

 tially removing this want, I would point out to our unprofessional 

 and non-scientific friends an interesting and practically useful 

 direction, in which to employ the few leisure moments they may 

 be able to devote to their instruments. 



The adulteration of the Foods and Drinks which we daily 

 consume, and on which our bodily health so much depends, 



