494 THE BLOOD-COKPUSCLES OF THE ANNELTDES. 



some length an account of the method we employed for collecting 

 the contents of the vascular system, so as to keep them free from 

 admixture with the perivisceral fluid ; the essentials of the method 

 being that a delicate pipette with, at one end of it, a very thin 

 bulb, and a sharp perforated point at the other, was used for 

 puncturing the great vessel, and extracting from it ' one or two 

 small drops, varying with the size of the annelid and its condition.' 

 ' The dissections were conducted under water ; and before the 

 cardiac organ was opened, which was done out of water, the fluid 

 which bathed the vessel was carefully washed away, and the sur- 

 face of the vessel was wiped with bibulous paper.' Dr. Davy de- 

 scribes the bodies seen in the red fluid thus obtained as follows : — 

 * Viewed under the microscope with a one-eighth inch power, 

 granules or minute corpuscles were seen scattered through it. These 

 varied a little in size ; their average size was about T1 J^th of an 

 inch, or about one-fourth that of the blood-corpuscles of man. Each 

 corpuscle had a luminous centre and well-defined outlines faintly 

 coloured red or yellowish red. The colouring matter, it was pretty 

 clear, was contained within the cell. After some doubt and many 

 trials, this was the conclusion we arrived at — that the fluid owed 

 ' its colour, either altogether or in great part, to those corpuscles. 

 I did not at the time entirely agree with Dr. Davy's views, the 

 exceedingly small size of these bodies making me adverse to calling 

 them by the same name as any indubitable ' blood-corpuscles ' of in- 

 vertebrata ; whilst two non-quantitative peculiarities observable in 

 many of them compelled rne to consider them ' lifeless,' in a more 

 thoroughgoing sense than it has ever been proposed to consider 

 even the mammalian red blood cell. These two peculiarities were, 

 firstly, the presence in many of these spheroids of concentric 

 striation, reminding one of the similar lines in the much larger 

 amyloid bodies from the prostate and the walls of the cerebral 

 ventricles ; and secondly, the occupation of the centre of many 

 of them by a rough-hewn, solid, and therefore functionless, dot of 

 yellowish-red pigment. These coloured bodies are strikingly like 

 the pullulations produced in mammalian, and other red blood- 

 corpuscles, by the action of tannin, described by Dr. Roberts. 

 I thought then, and know now, that a large proportion, if not the 

 whole, of these bodies were due to retrograde metamorphosis ; and 

 knowing then that the more care (we took too much care) was 



