1816.] during the Year 1818. 69 
1. Sir Everard Home has given an account of the organs of 
respiration in aclass of animals intermediate between the pisces and 
vermes, and in two genera of the last mentioned class. In the 
lamprey the organs of respiration have seven external openings on 
each side of the animal. These lead to the same number of oval 
bags, the inner membrane of which is constructed like the gills of 
fishes. These organs are inclosed in a cartilaginous thorax, and a 
pericardium acting the part of a diaphragm, by the actions of which 
the water is admitted and expelled. 
In an animal brought from the South Sea by Sir Joseph Banks, 
intermediate between the lamprey and myxine, but constituting a 
particular genus, the external openings and bags are the same as in 
the lamprey, but there is no thorax. The water is drawn in and 
expelled by the elasticity of the bags. 
In the myxine there are only two external openings and six 
lateral bags on each side, to which there are six tubes from each of 
the openings. 
In the aphrodita aculeata there are 32 openings on each side. 
These all open into a large bag immediately under the skin and 
muscles of the back, which is only separated from the cavity of the 
abdomen by a strong cartilaginous membrane; but there are two 
rows of spherical cells projecting into the cavity with very thin 
membranous coats. A ccecum from the intestine is lodged in each 
cell. These appear to be the principal respiratory organs, 
In the leech there are 16 orifices on each side of the belly, which 
lead to an equal number of spherical cells, placed between the 
abdominal muscles and the stomach. 
2. Sir Everard Home has ascertained that both the lamprey and 
myxine are hermaphrodites, 
$. Dr. Wilson Philip has published two curious papers, in which 
he relates a great number of experiments made in order to deter- 
mine the principle on which the action of the heart depends. He 
has shown that both the brain and spinal marrow may be removed 
without affecting the motion of the heart; but that if they be sud- 
denly destroyed, as by crushing them, the motion of the heart is 
affected. He explains these apparently contradictory experiments 
thus; in man there are three systems—the sensorial, the nervous, 
and the muscular, all independent of each other, but capable of 
affecting each other. In his second paper he shows that a stimulus 
applied to the brain in general accelerates the motion of the heart ; 
but that the action of the voluntary muscles is only excited by stimu- 
lating the part of the brain from which their nerves proceed. 
Ganglia, in his opinion, convey to the nerves which proceed from 
them the united energy of all the parts of the brain from which 
nerves going to them proceed, and they have no other use. 
4. Mr. Clift has ascertained, by a set of experiments on carp, 
that the brain of that fish may be removed, and the spinal marrow 
destroyed, without stopping the motion of the heart; but the action 
of the voluntary muscles was immediately destroyed. He found 
