E RRATA. 



r 



Page 114, first column, line 2G, fruiu 

 above, iusert the words "cover glasses" 

 after the word "preferred." 



rage 119. first colunin, lines 29 and 

 34, from above, read "2-5 umiiii" and 

 ''30-200 mmm," instead of "2-5 mm 

 and "30-200 mm/' respectively. 



Tage 120, second column, line 10, from 

 above, read **Agglomerative," instead of 

 "Agglomeratur. 



»f 



)» 



Page 124, first column, line 21, from 

 below, read "Two main types," instead of 



•"the two main types." 



