482 [March 19, 



appear to be furnished with perfectly plain envelopes, composed of a 

 simple homogeneous membrane, without distinction of parts. But, 

 as will appear from the observations here to be related, when the 

 blood is treated with a solution of magenta (nitrate of rosanilin) or 

 with a dilute solution of tannin, the corpuscles present changes which 

 seem irreconcileable with such a supposition. 



Attention is first asked to the effects of magenta. When a speck 

 of human blood was placed on a glass slide and mixed with a drop 

 of a watery solution of magenta*, the following changes were ob- 

 served. The blood-disks speedily lost their natural opacity and 

 yellow colour; they became perfectly transparent, and assumed a 

 : faint rose colour ; they also expanded sensibly, and lost their bicon- 

 cave figure. In addition, a dark-red speck made its appearance on 

 some portion of their periphery. The pale corpuscles took the colour 

 much more strongly than the red ; and their nuclei were displayed 

 with great clearness, dyed of a magnificent carbuncle-red. Many 

 of the nuclei were seen in the process of division, more or less ad- 

 vanced ; and in some cells the partition had resulted in the produc- 

 tion of two, three, or even four distinct secondary nuclei. 



These appearances were first observed in freshly-drawn blood from 

 the finger. Subsequently blood from the horse, pig, ox, sheep, deer, 

 camel, cat, rabbit, and kangaroo was examined in like manner. The 

 effect on the red corpuscles (to which all the observations hereinafter 

 recorded are exclusively confined) was in each instance the same as 

 n human blood. 



The nucleated blood- disks of the oviparous classes, when treated 

 similarly, yielded analogous results. The coloured contents were 

 forthwith discharged ; the central nucleus came fully into view, and 

 assumed a deep-red colour; the corpuscles expanded, they lost 

 something of their oval form, and approached nearly, or sometimes 

 quite, to a circular outline. Lastly, there appeared on the periphery 

 a dark-red macula, of a character and position resembling that seen 

 on the mammalian blood-disk. Such a macula was detected in the 

 fowl, in the frog, and in the dace and minnow, 



* The solution I found to answer best in these experiments was a nearly satu- 

 rated solution of nitrate of rosanilin, made by boiling the salt in water, and 

 filtering after it had stood twenty-four hours, then diluting slightly with water to 

 prevent precipitation. 



