from which its elongation and contraction is derived, 67 



demonstrated in the annexed drawing ; since I cannot 

 believe Mr. Bauer has been led into any error upon this 

 occasion ; as no error has been detected in his microscopical 

 observations for so many years continued, and the accuracy 

 of his representations, of what he has seen, no one can 

 doubt. 



It is a curious confirmation of the acuteness of his eye, and 

 the accuracy of his glasses, that Leuwenhoek, who used a 

 single microscope, and says it is the best that can be made, 

 since the magnifying glass is the smallest speck that can be 

 seen, declares a muscular fibre to be made of globules less 

 than the red globules of the blood ; and Dr. Monro of 

 Edinburgh, who published his microscopical observations on 

 nerves and muscles, in the year 1783, made chiefly in the 

 solar microscope, goes so far as to consider muscular fibres 

 to be the continuation of nervous fibres, and gives an en- 

 graving of the mode in which the one terminates, or is lost 

 in the other. Dr. Monro, it is evident, had never seen a 

 single fibre either of a nerve or muscle, only fasciculi of them, 

 and found them so much alike as to be led to consider them 

 the same. Both Leuwenhoek and Monro, from the want 

 of a micrometer, were left to guess at relative dimension, 

 and in such guesses were often very unsuccessful. 



The globules in the nervous fibre being smaller than in 

 the muscular, oversets Monro's theory of their being the 

 same ; but that both authors, with means so very inadequate 

 to those employed by Mr. Bauer, should have made such 

 approaches to the truth, is highly creditable to them, and 

 must prove highly satisfactory to Mr. Bauer, as well as to 

 the public. 



