1894] MICROSCOPICAL JOURNAL. 17 



that may be easily measured by any person having the 

 requisite skill and apparatus. 



The difference between the highest and lowest aver- 

 ages of 50 corpuscles is .000015 or 1-66666 inch, which 

 approaches more nearly the limit of micrometric meas 

 urement, though probably not beyond it. 



The difference between the highest and lowest aver- 

 ages of 75 corpuscles is .000012 or 1-83333 inch, which 

 approximates the limit of micrometric measurement. 



The difference between the highest and lowest aver- 

 ages of 100 corpuscles is .000009 or 1-111111 inch, which 

 is within the limits of personal and instrumental error, 

 according to the highest living authority upon this sub- 

 ject, who writes in substance, that it is easy to measure 

 1-50000 inch, but to be sure of 1-100000 inch is not pos- 

 sible. 



The conclusion to be deduced from the above figures 

 is obviously that, when a sufficient number of corpuscles 

 are measured, there appears to be an average size which 

 varies within very narrow limits, which may possibly be 

 accounted for or at least is consistent with personal and 

 instrumental errors ; for though I have carried out the 

 figures to the sixth decimal place, I have not trie pre- 

 sumption to declare that the results can be relied upon 

 farther than the fifth place, and have carried out the fig- 

 ures to the sixth only to insure accuracy in the fifth so 

 far as possible. Another conclusion is, that granting for 

 the moment that it is possible to identify blood by meas- 

 urements of the red corpuscles, of which I am by no 

 means satisfied, it is reckless in the last degree, if not 

 criminal, to express an opinion upon the measurement of 

 less than 100 corpuscles. To express an opinion upon 

 the measurement of only 10 corpuscles, as lam informed 

 has been done in this section within the last year or two, 

 to take the most charitable view of the subject, betrays 

 such culpable ignorance of a subject involving such mo- 



