1898.] MICROSCOPICAL JOURNAL. 205 



EDITORIAL. 



Limitation. — There is a definite limit to microscopic 

 vision. Abbe and Helmholtz attribute this to the nature 

 of lig"ht for they despair of resolving* lines closer 

 tog-ether than the leng^th of half a wave of lig"ht. 

 The hig-her the mag-nification the smaller the speck 

 that can come into the field of vision at once. In a mag-nifi- 

 cation of 50 diameters the picture represents 1-8 inch of 

 space ; in 100 diameters, 1-16 inch; in 1,000 diameters, 1-150 

 of an inch which is too small to be at all visible to the naked 

 eye. The g-erm within the nucleolus of a cell has a structure 

 too minute to be seen by any microscope yet made. The 

 human ovum is 1-120 inch in diameter and made up of a 

 countless number of cells. The yolk which encloses the 

 nucleus and its nucleolus within can be seen but not the 

 structure of the latter. 



Bacteria in Ground W^ater. — The readiness with which 

 bacteria may be conveyed to wells in sub-surface water 

 has been shown in some experiments made on the Rhine 

 nearStrasburg by Prof. E. Pfuhl. Two kinds of bacteria, 

 neither occurring- in the Rhine, were placed in a shallow 

 pit nearly full of water and in one hour one species had 

 passed through twenty-four feet of gravel to a second pit, 

 the other species appearing in the second pit within 

 two hours. 



Quekett Club. — 3f)2nd meeting, October 21. Messrs. 

 Beck exhibited a series of their new British students' 

 model microscopes. Messrs. Watson showed their Fram 

 microscope with sliding bar to the stage. George Massee 

 described the growth, fructification and life-cycle of cer- 

 tain fungi which usually can be found in the foray in 

 Epping Forest, but which this year were absent on ac- 

 count of the dryness. He showed colored diagrams, dry 

 specimens from Kew herbarium and slides. It was an- 

 nounced that W. Bryce Scott of Ontario had sent a 

 quantity of West India coral sand, and diatomaceous 

 earth from Nova Scotia, North Atlantic Cable dredgings 



