158 THE MICROSCOPE. 



Frey says they are the ^-g^o to rsVo" °f an inch. 

 Welcker says they are the -g-^^ of an inch. 



Where is the exact size to judge by? The red corpuscles are 

 also subject to change in size by the varying changes in the blood 

 and by many drugs. Wagner, in his General Pathology, gives a 

 long list of remedies that when administered change the size of this 

 corpuscle. How delicate is it, also, to the various reagents used in 

 microscopical work! I have seen red corpuscles as small as the 

 -g^^ of an inch and as large as the ^Vo - °f an mc ^- I have never 

 measured red blood corpuscles in lots of fifty each and had any 

 two exactly alike, although using a delicate cobweb eye-piece 

 micrometer and a one-fiftieth objective. 



Listen to what Mr. Woodward, of Washington, says: "The 

 average of all the measurements of human blood I have made is 

 rather larger than the average of all the measurements of dog's 

 blood. But it is also true that it is not rare to find specimens of 

 dog's blood in which the corpuscles range so large that their average 

 size is larger than that of many samples of human blood." 



Human blood cannot be told from dog's blood, except under 

 favorable conditions, and not invariably then. For the sake of 

 microscopy it is a pleasure to know that only four men are ready to 

 make such statements. There are a 'score of men in this country 

 with glasses equal, at least, to Dr. Up de Graff's, who would testify 

 directly opposite to him on this point. If Dr. Up de Graff is ready 

 to receive a number of pieces of cloth, labeled and stained, respec- 

 tively, with human and dog's blood, under favorable and unfavor- 

 able- circumstances, this journal will see to it that said cloths are 

 prepared with accuracy by competent parties. If he succeeds he 

 shall receive all the glory these columns can sound forth, but if he 

 fails he will be referred gently to his Wellsboro testimony. 



[The only way for you to do, Dr. Up de Graff, is to pack up 

 your machine and come and make us all a good visit at Ann Arbor. 

 I will argue and argue, and eat oysters all night, if necessary — but 

 be sure and bring Mrs. Up de Graff with you.] 



