Joyce's very realistic depiction of Bloom's bowel movement in Calypso includes one vividly personal detail: an ongoing struggle with "constipation." Bloom credits his deliverance from this ailment on June 16 to consumption of a popular herbal laxative, "cascara sagrada."
As he sits reading Philip Beaufoy's story in Tit-Bits, Bloom holds back, "yielding but resisting." Halfway through the story, "his last resistance yielding, he allowed his bowels to ease themselves quietly as he read, reading still patiently, that slight constipation of yesterday quite gone. Hope it's not too big bring on piles again. No, just right. So. Ah! Costive. One tabloid of cascara sagrada." "Costive" is a less familiar form of "constipated," derived ultimately from the same Latin root. The placement of the word in Bloom's thoughts suggests that he may be recalling language from an advertisement or from the label on a bottle of pills.
Cascara sagrada, Spanish for "sacred bark," refers to the dried and pulverized bark of an understory buckthorn tree, Rhamnus purshiana, that is native to the northwestern United States and British Columbia. Chemicals in the bark stimulate peristalsis very effectively by increasing water retention in the colon, a fact which Native American tribes in the area have exploited for centuries. Spaniards exploring the area in the 1600s tried it for themselves and bestowed the honorific name. An American pharmaceutical company, Parke-Davis, began marketing the powdered bark in the 1870s, and before long began exporting it to Europe. It was extremely popular in the early 20th century and remains so today, though the US Food and Drug Administration in 2002 banned its use in over-the-counter laxatives.
The properties of this herbal laxative fit well with Joyce's account of Bloom's peristalsis, but he adds one puzzling detail: "Hope it's not too big bring on piles again." Piles are hemorrhoids, but what is "it"? If the reference is to "constipation," Bloom is perhaps thinking that the hemorrhoids he has suffered in the past have been caused by straining to evacuate his bowels—and hemorrhoids can indeed be caused in this way. But it would be strange for Bloom to hope that his constipation is not "too big" just after realizing that yesterday's constipation is "quite gone." More likely, "it" is the dosage of cascara sagrada ("one tabloid") he has taken. This interpretation fits the context better, and may cohere with the potentially violent actions of cascara sagrada, which is contraindicated for people with hemorrhoids.