1894.] MICROSCOPICAL JOURNAL. 309 



OBSERVATIONS ON THE MESENTERY. 



At this point, I transferred my observations to the 

 mesenteries of frogs, instead of the foot-webs, but before 

 doing so I made a thorough examination of the corpus- 

 cles of the frog's blood with the following results. 



Besides the oval red corpuscles I found that there are 

 two distinct kinds of white corpuscles present in the 

 blood which may be described as follows : 



The most numerous variety are large, about 1-1200 in. 

 in diameter, finely, granular, irregular in outline, having 

 fine projections from its surface and having a two, but 

 generally three part nucleus, surrounded by finely gran- 

 ular protoplasm. 



The second variety is less numerous, more coarsely 

 granular, smaller, and contains one nucleus. The granu- 

 les in the protoplasm are sometimes seen to rush from 

 one side of the corpuscle to the other. The corpuscle 

 exhibits active movements which are, of course, amoeboid, 

 as does also the larger variety. Unfortunately, when 

 watching the process of inflammation, I could not distin- 

 guish the difference between these two varieties for the 

 following reasons. 



1. In a small vessel white corpuscles are not present 

 in sufficient numbers to detect the two varieties, and 

 when present in large numbers, so crowded together as 

 to make it impossible. 



2. The nuclei of the white blood corpuscles cannot be 

 clearly made out without the use of reagents, which, if 

 used, would interfere with the process of inflammation. 



I found it necessary as stated in order to clearly de- 

 fine the nuclei and to see their number to add to the 

 blood a little dilute acetic acid, which clears up the sur- 

 rounding protoplasm, and brings the nuclei very clearly 

 into view. If desirable, magenta may now be added 

 which will stain the nuclei very beautifully. Adding di- 

 lute alcohol will also bring the nuclei into view. 



