62 Transactions of the Royal Microscopical Society. 
in its supjoort, it is singular that he should have entirely overlooked 
the only unmistakable evidence of the existence of a cell-wall, 
namely, the double contour, which the coloured blood-corpuscle 
shows under the conditions above mentioned. 
With the view of bringing the still- existing controversy regard- 
ing the structure of the coloured blood-corpuscles somewhat nearer 
to a close, I instituted, during the summer and autumn of 1873, 
a series of microscopical researches upon this subject. The special 
material used for this purpose were those giant blood-corpuscles of 
the Amphiuina means, or tridactylum* as the animal is called by 
European writers, and also those of the Frog and of Man. The 
examinations on the latter I have only lately carefully repeated. 
The former attain the enormous size of from to two 
length, and from to yffo breadth ; thus exceeding 
in magnitude very considerably even those of the Proteus angui- 
neus. 
Knowing that the blood-corpuscles of this animal had never 
been thoroughly investigated, I devoted a great deal of care on 
their examination. A considerable number of animals of all ages 
and sizes were used. While some of them scarcely measured from 
five to six inches in length, and served for the study of the deve- 
lojoment of their blood-corpuscles, others had attained a maximum 
length of three feet, and a thickness equalling that of the wrist of 
a large man. I was also favoured, by chance, in obtaining the eggs 
of the animal, enabling me to examine the blood of the embryo. 
As regards the application of the vapours of certain reagents 
* The Amphiuma tridactyhm at New Orleans, vulgarly called “congo-eel” or 
“ congo-snake,” belongs to the order Urodela of the Amphibia, and ought not to be 
confounded with the conger-eel, a true fish, found on the coasts of North America, 
Great Britain, and France. From what I know, I presume that the name congo- 
eel or congo-snake, applied by the people to this animal, has originally been 
derived from the Congo negroes, formerly imported into this country from the 
Congo region on the coast of Guinea in Ahica. It is very likely that these 
negroes, like some of their descendants at the present day, as I have been told, 
were in the habit of using the Amphiuma for food, and thus engrafted their 
name upon it. Although the popular belief of the venomous bite of the animal 
is unfounded, it is nevertheless savage enough to bite eagerly at anything held 
before it. Its skin is very smooth and slippery, not allowing a firm hold upon it. 
For this reason, to obtain its blood for examination, I placed the animal in a sack 
of coarse material, in which its movements are limited. An assistant then takes 
a good hold of it, through the sack, directly behind its head, with one hand, and 
around the belly with the other ; the tail is then pulled out from the open end of 
the sack, and after being wiped perfectly clean, the extreme point of it is clipped 
off with a pair of scissors, until a small drop of blood, escaping from the caudal 
artery, appears. This method of obtaining the fresh blood is the best of all I have 
tried, for in vigorous adult animals blood seldom appears from an incision into the 
skin, or even into the underlying muscles. It seems that in this animal the 
arterioles and venules possess uncommonly strong muscular coats, by the con- 
traction of which a hemorrhage is prevented. An account of the descriptive 
anatomy of the Amphiuma tridactylum, only lately issued by Dr. C. H. Hoffmann, of 
Leyden, will be found in Dr. H. G. Broun s ‘ Klassen uud Ordnungen des Thier- 
Eeichs, &c.,’ a work still in progress of publication. 
