162 THE MICROSCOPE. 



valves which fit together along the median line running from 

 end to end (and which shows so conspicously), much as the 

 cover tits upon a pill-box. 



The cavity or resulting enclosure is of many different shapes 

 in different species of diatoms and serves for the reproduction 

 of the species. One of the valves is always older than the other 

 and the hoop of the older valve partly encloses the younger. 

 As growth progresses the outer hoop slides off the inner one 

 until often there is but very little overlap. 



The species is perpetuated and increased by each frustule di- 

 viding into two frustules and so multiplying its numbers in- 

 definitely. After the death of each plant the frustules remain 

 and may last for centuries if buried under favoring conditions 5 

 or otherwise preserved. 



A METRIC STUDY OF TWO THOUSAND CHECK 



SIGNATURES. 

 By De. Marshall D. Ewell, 



CHICAGO, ILL. 



The various methods of committing forgery and the means 

 available for its detection were discussed by the writer in the 

 American Law Register, Vol. xxix, 1890, p. 553. In that paper 

 we stated that perfect identity of two signatures is very strong, 

 if not conclusive, evidence of fraud, referring to the famous 

 Howland will case, which will be found abstracted on p. 562 of 

 the same volume. 



A similar question arose in the case of the will of late Senator 

 Joseph E. McDonald, recently tried at Nobleville, Indiana, in 

 which the verdict was that the will was a forgery. 



In the preparation of that case it was thought expedient to 

 investigate the question of the length of signatures written in the 

 ordinary course of business by the same person, with the view 

 of ascertaining, if possible, the law, if any, governing the same. 

 With that end in view the writer measured the length of 700 of 

 his own checks drawn on the First National Bank of Chicago 

 between the years 1884 and 1888, and also 300 checks drawn on 

 the Merchants' Loan and Trust Company in the years 1891 and 

 1892. The former were drawn on smaller blanks than the lat- 



