Top: Cow-milker infected from the teats of a cow with natural cow-pox. Large depressed vesicle with a small central crust, tumid (swollen) margin, surrounded by well-marked areola and considerable surrounding induration (hardness associated with swelling)

Bottom: Same case, one week later. Reddish brown crust typical of recovering cow-pox cases, on a reddened elevated and indurated base.

Many mammalian species have members of the Orthopoxviridae that are specialized to exist within their systems - humans have smallpox, cows have cowpox, monkeys have monkeypox, and so on (note: chicken pox is NOT a member of this group - its name comes from an old English word meaning "Itchy", and is completely unrelated).

However, sometimes, the similar viruses can cross species barriers, as in the case of cowpox. Though the viruses are specialized to their host species enough that they don't easily spread between atypical hosts, they're related enough that once an individual is infected with one pox virus, their immune system is able to to recognize and fend off the whole lot of them. This is why, with the assistance of cowpox (Vaccinia) cultures in administered vaccines (rather than all of humanity having to be in direct contact with cows...), smallpox was able to be eradicated in the wild.

A Text-Book of Bacteriology, including the Etiology and Prevention of Infectious Diseases. Edgar M. Crookshank, 1897.

The Juvenile Hoatzin (Opisthocomus hoazin)

It should first be noted that all birds are dinosaurs (order Saurischia, clade Theropoda), not just descendents of dinosaurs - modern genetic analysis strongly supports this cladistic organization. But given what we're too often taught in schools, birds and dinosaurs are hard to reconcile in many peoples' minds.

The juvenile hoatzin, however, makes it easy to see the reptilian traits that once dominated the early birds, and displays the unused genetic codes that lurk in the genome of modern avians. When they hatch, they're equipped with lizard-like claws in front of their wings. Their use is described here, but in short, they use them to return to their nest and avoid predators. Their claws disappear by the time they leave the nest, having grown together into the metacarpals that support the wing structure.

Another fascinating trait of the hoatzins is their vegetarianism and their digestive tract. They have gut flora and fermentation similar to ruminants, which no other bird has. This is actually what leads to their being called "stink birds" - they exude a lot of stench with the fermentation process. The gut fermentation is so important to the hoatzin that the flight muscles attached to their keel are significantly reduced, to allow for more space for the stomach. They are weak flyers because of this. After a large meal, an adult hoatzin can spend up to two days doing almost nothing, allowing the leaves and greenery to have their nutrients released by their symbiotic gut flora.

Images: Top: Attitudes of the juvenile hoatzin while climbing Second row, left: Hoatzin nest with two eggs - Note proximity to water Second row, right: Two hoatzin chicks preparing to dive, after appearance of threat from above Third row, left: Hoatzin chick demonstrating strong swimming abilities Third row, right: Hoatzin chick demonstrating poor locomotion on land Bottom: Detail of hoatzin chick climbing, using neck, feet, and claws.

Tropical Wild Life in British Guinea, Vol 1. Curated by William Beebe, 1898.

Rock Scorpion - Hadogenes troglodytes

This scorpion has the longest recorded body length of all known scorpions. It hasn't been extensively researched, but is known to cause more inflammation than pain at sting sites, and there have been no known fatalities from it. It lives in Southern Africa.

Popular Science Monthly: Volume 51. 1897.

1897 rock scorpion popular science monthly volume 51

Representative cephalopoda (cuttlefish, squid, octopus) of the Gulf of Naples.

I Cefalopodi viventi nel Golfo di Napoli (sistematica). 1897.

I'm sorry, I know this is a legit form of artificial respiration (though not a common one...accordion-baby and modified CPR is more effective), but there's nothing about either of these photographs that looks like it should be the way it's presented - especially doctor-man's eyes in the first one.

A Text-Book on Practical Obstetrics comprising Pregnancy, Labor, and the Puerperal State, and Obstetric Surgery. Egbert H. Grandin and George W. Jarman, 1897.

A Text-Book on Practical Obstetrics Comprising Pregnancy, Labor, and the Puerperal State, and Obstetric Surgery. Egbert H. Grandin & George W. Jarman, 1897.

The Cestracion genus is now three separate genera, all in the Sphyrnidae family. Those are the hammerhead sharks.

The Notidanus is an extinct genus of the family Hexanchidae, the most primitive family of sharks. Though once incredibly diverse, the only extant members now include the cow sharks and frilled sharks.

Lots and lots of fox! Tenrec = Fennec fox

The Animal Kingdom. Hugh Craig, 1897.

Fucus-like sea-horse. "Fucus" is a genus of brown algae...it's not like a slimy algae you'd find in a pool, but what most people call a "seaweed". Many seahorses that live in cooler environs are shaped and colored similarly to endemic plant life. More tropical seahorses tend to be the more brightly colored ones, just like other bony fishes.

The Royal Natural History. Richard Lydekker, 1897.

Polar bears fighting over a caught seal.

The Animal Kingdom. Hugh Craig, 1897.

The Animal Kingdom. Hugh Craig, 1897.

P.T. Barnum's "Forest and Jungle" is told in story form, aimed at kids. The guy encountering the Secretary Bird is a tough Texan cowboy-type, with low regard for most animals he's encountered so far. This bird, though? He doesn't even try to kill it, but if he were he to come a yard closer to her nest, she would "attack him with the ferocity of a tigress protecting her cubs."

From Forest and Jungle or Thrilling Adventures in all Quarters of the Globe; an illustrated history of the animal kingdom. By P.T. Barnum, 1897.

The secretary bird is way up there on my favorite animal list, at least in terms of being a badass goes. These crazy birds will stomp the hell outta the most venomous snakes in Africa, and sometimes it's not even to eat them; they're not keen on snakes even existing in their territory when they have chicks in the nest, let alone close enough to hunt their babies.

From Forest and Jungle or Thrilling Adventures in all Quarters of the Globe; an illustrated history of the animal kingdom. By P.T. Barnum, 1897.