SCIENTIFIC SUMMARY. 
219 
mammalia. From tliis we learn, tliat among the lower mammalia there is a 
remarkable diversity with respect to the distribution of the rods and cores. 
Whilst most of our larger domestic animals, especially the horse, ox, sheep, 
pig, and dog, present an arrangement of those elements resembling that 
which is seen in the human subject and in apes [except, of course, in the 
absence of the macula lutea ], the cones, according to Herr Schultze’s obser- 
vations, are entirely wanting in bats, hedgehogs, mice, moles, and guinea- 
pigs. A sort of intermediate condition is met with in the cat, rabbit, and 
rat, in which animals are found either very slender true cones, as in the 
cat, or merely indications of them, as in the rabbit. But, in any case, the 
rods preponderate so much that the cones among them may readily be over- 
looked. In the rat, the rods are the longest and slenderest which Herr 
Schultze has yet found. 
Structure of the Liver. — Dr. Lionel Beale’s opinion as to the structure of 
the vertebrate liver has been recently substantiated by the researches of 
Herr Hering. This histologist states that the liver is constructed like the 
other secreting glands. It is of the tubular type, with canals, anastomosing 
in every direction, and having a tendency to form a series of networks. 
Like other secretions, the bile travels along glandular canals surrounded by 
glandular cells. It is easy (he says) to observe this arrangement in the 
livers of vertebrates. Five or more cells are disposed in simple layers around 
the circular and minute aperture of an hepatic utricle seen in transverse sec- 
tion. This arrangement loses itself insensibly in that variety of structure 
in which there are no utricles properly so called. Occasionally may be seen 
four, three, or even only two cells, uniting to form a biliary canal. The 
Russian anatomist denies the existence of hepatic trabeculae of biliferous 
capillaries, and believes that the biliary cells are persistent. He looks upon 
serpents’ livers as the only organs for minute inquiries upon the subject. — 
Vide Lancet Record of Science, March 2. 
Blood-poisoning after Surgical Operations. — The researches and experi- 
ments of M. Maisonneuve prove that nearly 95 per cent, of the sequelae 
of surgical operations result from the action of morbid products developed 
in the wound, and subsequently absorbed into the system. He puts forward 
his ideas in the following systematic fashion : — 1. The blood and other 
animal fluids, when exposed freely to the air, or in contact with aqueous 
substances, soon lose their vitality. 2. Once dead, they are liable to 
putrefy under the influence of heat, moisture, and air. 3. The products of 
such putrefaction are highly poisonous. 4. It is the same with such secre- 
tions as the urine, bile, and intestinal juices. 5. In infiltrating the permeable 
tissues with which they are in contact, these poisoned liquids give rise to 
gangrene, erysipelas, &c. 6. These same liquids, either by themselves or 
mixed with the special products of inflammation they provoke, can, in 
entering the circulation, alter the blood and disturb important functions. 
7. After their expulsion from the general blood-vessels, they may remain in 
the capillaries, the parenchymata, serous tissues, &c,, and give rise to abscess, 
anthrax, &c. 8. The entirety of the disturbances constitutes surgical fevers. 
To prevent these terrible consequences of operations, M. Maisonneuve sug- 
gests the adoption of the subcutaneous method, and the employment of Ml 
means of preventing putrefactive processes. 
