232 On the Blood-cor puscles of the Cyclostoviata. 



find their red blood- corpuscles large and oval, and similar to 

 those of the skate or dogfish. On consulting Johannes 

 Miiller (Vergl. Anat. d. Myxinoiden) I found that he had 

 noted and figured the oval coi-puscles of Myxine, but without 

 measuring them or calling attention to their points of contrast 

 with those of Petromyzon. Dr. Giinther, in his article 

 " Ichthyology " in the ' Encyclopsedia Britannica,' sajs 

 accurately that "the corpuscles of Petromyzon are round," 

 but proceeds to say that the corpuscles of the Cyclostomes 

 are exceptionally small, taking it for granted doubtless that 

 the two genera agree in this respect. 



I find the red corpuscles in Myxine to be thin, flattened, 

 oval plates, with a central nucleus, which is sometimes round, 

 more often elongated and rod-like. 



Their dimensions are as follows : — ■ 



millim. 



Length -025 to -028 



Breadth about "01 



Thickness „ -003 



The nuclei stain very quickly and intensely with magenta. 

 The white corpuscles are of about the same size as those of 

 man. They are irregular or amoeboid in shape, and have a 

 very large granular nucleus. Sometimes the whole corpuscle 

 is granular, and then appears to be devoid of a nucleus. 

 The white corpuscles are remarkably numerous, being not 

 less than three fourths as numerous as the red, and sometimes 

 equalling them in number. 



In Petromyzon marinus I find the red blood-corpuscles to 

 be circular, as stated. They measure about '013 to '014 

 millim. in diameter. Gulliver gives "019 for Petromyzon ; 

 but he very probably used another species. The nucleus is 

 small, placed not in the centre, but usually near the edge of 

 the disk, and stains very slowly and feebly in magenta or 

 hasmatoxylin. The white corpuscles are even more nume- 

 rous than in Myxine, being actually thrice or four times as 

 many as the red. Their nuclei are small and stain well, and 

 forms transitional in shape and size to the red corpuscles 

 seem to be recognizable. Some indeed are round, clear, with 

 excentric nucleus, and similar in size to the red corpuscles ; 

 others are quite small, one half the diameter of the former, 

 and with a central nucleus ; others, again, are large, granular, 

 and with the nucleus disproportionately large. 



In both genera the red corpuscles are very easily deformed. 

 The corpuscles of Myxine often seem to tail off into a point 



