It is 1:15 am in Perth, but only 6:15 London Summer Time so I can still say this entry is on the 150th anniversary of Darwin's book "The Origin of Species". I have been too busy to spend a lot of time researching Darwin's illness but it is very easy to conclude that he had a gastric illness by searching the Darwin on-line archives located
here. If one searches for "stomach" or "my stomach" you can find about 70 instances where he refers to his illness. If one searches for "heart", "my heart", "palpitations", "pulse" etc. you can find only a few references and most are to do with his normal emotions rather than his physical organic cardiac symptoms. Thus it seems to me that the idea of a cardiac illness is rather over-rated (notably some kind of sympathetic or parasympathetic disturbance caused by chronic Chagas' disease).
However I do concede that Darwin refers often to "flatulance" but rarely if ever to disturbances of the bowels e.g. diarrhoea. Thus it seems that his flatulance symptoms are actually a feeling of distension in the episgatrium which are commonly related to and releived by aerophagia (swallowing air) and eructation (burping) respectively. This type of symptom is common in acidic conditions such as duodenal ulcer and is especially so when accompanied by hiatus hernia and gastro-oesophageal reflux disease (GERD/GORD). But the nausea and vomiting he often suffered from makes gastritis and duodenal ulcer a likely associated cause.
Flatulence can also be due to lactose intolerance and this has been invoked to explain his illness by several authors. This year, Mike Dixon finished a book (Darwin in Ilkly by Mike Dixon and Gregory Radick) where lactase deficiency is championed (I have not read the book yet so cannot give an opinion on the evidence). If Darwin did have milk intolerance then it seems to me that he would have worked out himself that he was lactose intolerant e.g. drink milk = abdominal gas and +- diarrhoea and farting with a lead time of an hour or two. It is interesting to speculate that if lactose intolerance is genetic, then it could be diagnosed on his remains at some future date.
Getting back to my ulcer/Helicobacter hypothesis now, I have previously noted that he took bismuth and various antacids at the hight of his illness. Also, when he was especially unwell, his father prescribed "calomel", which is mercury, yet another heavy metal. At other times he took arsenic. Of course everyone took these things in the early 19th century because there weren't any other antimicrobials. But each of these heavy metals might have been expected to kill H.pylori in the stomach and cause a remission if taken daily for 2-4 weeks.
So, I admit that I am curious about the language Darwin used and the meaning of his "flatulance". I have several secret strategies for finding this out. If it was colonic anal rectal expulsion of air then the case for a carbohydrate malabsorption (lactose intolerance) is strengthened. This could be correlated with a diary of his illness to see if milky foods could correlate with his apparent gassy problems.
Once more I have not discussed psychosomatic causes of his symptoms - there does not seem to be any need to invoke this.
By the way, there is quite a nice new book out by John Van Wyhe which contains facsimiles of some original Darwin research notes in little pockets on the pages. Nice work John. My clock just struck 2 am - time to go.