The first five chapters have the most interest.
1. What is a Werwolf? The opening sentence almost kills the title: "To this there is no one very satisfactory reply." The author, who was clearly a devoted believer in most matters supernatural explains why he is right to believe as he does, roaming through history and locality and generally suggesting that, to have so many tales and reports of werewolves, proves the existence of such creatures. He points to the possibility of an early religious or ritualistic origin but then gets diverted away from shamans disguising themselves as beasts to shamans becoming beasts. Various notable referees to were-creatures are brought in, from Pythagoras to Thomas Aquinas and the Bible. I rather lost interest when he brought in "Malevolent Forces" as "the originators of all evil."
2. Werwolf Metamorphosis Compared with Other Branches of Lycanthropy. If one already finds it difficult to believe in werewolves, then the presence of "wer-tigers" in Orissa, "wer-jaguars" in Arawak, "wer-leopards" in wherever Ashangoland was, and so on, will be difficult to swallow. Mr. O'Donnell gives some entertaining stories from India and what used to be the Dutch East Indies to prove his point that were-creatures abound. However, they read like tales to be told on a dark winter's night.
3. The Spirits of Werwolves. The chapter consists mainly of a story from Estonia about the ghost of a werewolf haunting a lonely forest road.
4. How to Become a Werwolf. Forget about being bitten by a werewolf when there is a full moon, herbs seem to be the answer. Asafoetida, parsley, opium, hemlock, henbane, saffron, aloe, poppy seeds, solanum seem to be the best bet if you fancy a lycanthropic adventure. There is also a poem to chant while stirring your broth. Another way of transforming is by having a werewolf ancestor - it runs in the genes, so it seems. A story from Montenegro is provided for enlightenment.
5. Werwolves and Exorcism. The author is not a great believer in exorcisms, and silver bullets do not get a mention. The use of more herbs rather than prayer and a holy book seems to be the solution. A story from Russia illustrates the problems of ridding oneself of a werewolf.
Following those chapters are several more on werewolves through Europe: the British Isles, France, Germany, Austria-Hungary and the Balkans, Spain, Belgium and the Netherlands, Denmark, Scandinavia, and Russia and Siberia. These chapters provide little information and form mainly a collection of scary stories about hairy things that go bump in the night and may eat you if it is not your lucky day. Overall the volume is a compendium of werewolf stories written in the style of the late 19th and early 20th centuries. OK for the occasional shiver.