1 Introduction In 2015, an on-site field investigation was conducted by the authors' research group to authenticate a batch of ancient Chinese medicinal decoction pieces that have been preserved in a rare collection at the Natural History Museum in London. These treasured artifacts comprise a portion of the Sloane Collection, and the nearly 100 Chinese medicinal specimens examined within provide an objective record of the real situation regarding Chinese medicinal materials in commercial circulation 300 years ago. The precious data from this collection provide an extremely valuable reference for research into the history of medicinal exchange between China and the West during the Age of Exploration, shedding light on the evolution and historical changes in the species used in Chinese medicine as well as the history of medicinal processing and decoction pieces. 2 The Sloane Collection and the British Museum The British Museum (Fig. 1) was established in 1753. Its collections originate from all of the major continents and range from antiquity to the present; the museum is in a leading international position in terms of the number of its artifacts. The story of the origin of the British Museum begins with Sir Hans Sloane. Sir Hans Sloane (1660–1753) was born in Ireland; he became an outstanding British doctor and served as the physician to the governor of Jamaica. Sir Hans's life was dedicated to scientific research, and he had a deep love for collecting objects, with a particular enthusiasm for plant and animal materials. His botanical specimens represent an embryonic form of the style used for voucher specimens in the modern day. His specimens formed the basis for many descriptions of new species and names adopted by the Swedish botanist Linnaeus, who laid the foundation for the modern system of binomial nomenclature. Sir Hans is credited with patenting the combination of chocolate and milk, which brought him a considerable income. This economic abundance supported his collections and his generous philanthropy.Figure 1: The British MuseumWhen Sir Hans Sloane passed away in 1753, his collection contained over 70,000 objects; amazingly, this substantial number does not even include his vast collections of botanical specimens, books, and manuscripts. At the time of his death, he bequeathed his vast collection to the nation. The British government honored his dying wish and built a museum to preserve this precious collection; thus, Sir Hans's collection became the foundation of the British Museum. Today, Sir Hans's contributions are memorialized through the dedication of place names such as "Sloane's Square" in central London. As the collections of the British Museum increased over time, the objects were divided to form the British Library, the Natural History Museum (Figs. 2 and 3), and the British Museum.Figure 2: The Natural History MuseumFigure 3: Entrance hall of the Natural History MuseumThe Natural History Museum is situated in the South Kensington district of London. The building itself is an architectural masterpiece designed by Alfred Waterhouse, and it was established and opened to the public in 1881. The Natural History Museum stores over seventy million objects, encompassing animals, plants, fossils, and minerals. Upon entry, visitors are greeted by a colossal dinosaur skeleton (Fig.4), and on the wall is a display of extinct ancient creatures and fossils. On the hall of the second floor, to the left is a white marble statue of Darwin, while to the right lies the cut surface of a North American redwood tree over 3 m wide; looking at its annual rings reminds us that time brings great changes. From the thousands of years in the history of man to the billions of years in the history of the Earth, visitors are inspired by the evolution of our world. Featuring permanent and temporary exhibits for the popularization of science, it can be visited continuously.Figure 4: Dinosaur skeleton hanging from the ceilingAccording to the introduction by our guide, the exhibits on display account for only one-tenth of the collection. If the entire collection were to be put on display, one would need to walk for 27 km to see all the exhibits. At the Darwin Research Center, the color of the plants against a snow-white background radiates the vitality of life. Upon entering the collection room, the temperature, humidity, and security are closely controlled. Many specimens from Sir Hans Sloane and Charles Darwin are stored within. An oil portrait of Sir Hans sits on the wall, with bright eyes and an aura of peace, calmly watching over and accompanying his collection of treasured artifacts (Fig.5). In the absence of special permission, ordinary visitors are not allowed to see this sacred scientific space. Because many of the specimens in the storehouse have not yet been authenticated, it is not possible to look up the items online; it is even hard to find all the information within the collection itself. Fortunately, the authors had been invited to examine the collection: a historic moment and a special opportunity (Fig. 6).Figure 5: Prof. Zhao with the portrait of Sir Hans SloaneFigure 6: The authors were invited to examine the collection in the closed areaPrior to our visit, the staff at the Natural History Museum had already prepared a number of specimens (Fig.7). A broad table with four cabinets of specimens was laid out, and within the cabinets, many boxes were stored. Each box featured transparent glass, and the size of each box varied depending on the specimens stored within (Fig.8). The specimen boxes were identified by four-digit codes, and each box was wrapped in a plastic cover with a bar code. Additional records of the collection were written in eighteenth-century English and occasionally French. The medicinal names featured an archaic style of Pinyin that is no longer in use; for example, Wu Yao (乌药 Radix Linderae) was labeled "u jo," Zhi Shi (枳实 Fructus Aurantii Immaturus) was labeled "cj xe," and Huo Xiang (藿香 Herba Agastachis) was labeled "ho hian." A number of specimens featured labels with English or Latin names, and a number of people had evidently attempted to authenticate the materials in the past. Although some items were identified inaccurately, such as a Ju Hua (菊花Flos Chrysanthemi) specimen that was labeled "camomilla," it is clear that these specimens have consistently attracted the attention of experts in botany and pharmacy.Figure 7: Sir Hans Sloane's plant collectionsFigure 8: Cabinets of specimen boxesMost of the specimens observed were decoction pieces. The collection contained commonly used Chinese medicines as well as herbs that are locally used in southern regions and a number of foreign medicinals. Based on the varieties observed, it appears likely that many specimens came from a pharmacy in southern China; thus, the collection likely reflects the real clinical situation in a particular region and time. According to the introduction from the caretakers responsible for the collection, these specimens were obtained for Sir Hans Sloane by the East India Company, and the current set represents only a portion of the original collection. These specimens offer evidence of historical changes in the species used in Chinese medicine. For example, in the case of the herb Mu Tong (木通 Caulis Akebiae) (Fig.9), the Chinese Ben Cao literature indicates that the species originally used was Akebia quinata (Thunb.) Decne. In the 1990s, renal failure was reported in Europe owing to the mistaken use of Aristolochia manshuriensis Kom as Mu Tong, and the topic of "Chinese herb nephrotoxicity" continues to arise in discussions of Chinese herbal toxicity.1 Based on this identification, it is clear that the Mu Tong medicinal material sent to Europe from China during Sloane's era was derived from Akebia quinata (Thunb.) Decne. Confusion with Aristolochia manshuriensis, known as Guan Mu Tong (关木通 Caulis Aristolochiae Manshuriensis), may thus have occurred during the Qing dynasty owing to of influence from the northern regions.2Figure 9: Mu Tong (木通 Caulis Akebiae)Opium poppy is very effective for relieving cough and stopping diarrhea. It was clearly recorded as early as the Song dynasty, and the Ming dynasty Bencao Gangmu (《本草纲目》 The Grand Compendium of Materia Medica) notes that it cannot be taken for a prolonged period of time.3 The extraction of morphine or opium from the poppy did not arise until later, in the period surrounding the Opium Wars. Currently, the poppy capsules on the market all show evidence of cutting by knife, and these cuts have become regarded as a special identifying characteristic in Chinese medicinal authentication textbooks. However, the outer capsule is intact in the specimens observed here, suggesting that the opium capsules of the time were not previously cut to extract opium for use as a drug. Customary differences between the northern and southern regions of China are reflected in the parts used for medicinal purposes of some plants in the observed specimens.4 Within this collection, the Chinese names are not standardized, meaning that a number of folk medicines used in southern regions can also be seen, such as Mu Bie Zi (木鳖子 Semen Momordicae), Zi Cao Rong (紫草茸 Lacciferi Secretio), and Chu Shi Zi (楮实子 Fructus Broussonetiae). Many characters are written in shorthand to save strokes, such as Lai Fu Zi (莱菔子 Semen Raphani) and Zhu Ling (猪苓 Polyporus) (Fig.10). Chinese herbal medicines are commercial materials, so the level of cultural sophistication varies among traders.Figure 10: Zhu Ling (猪苓 Polyporus)Foreign medicines are present in the collection, including Mo Shi Zi (没食子 Galla Halepensis), Ru Xiang (乳香 Olibanum) (Fig.11), Ding Xiang (丁香 Flos Caryophylli), Ying Su Qiao (罂粟壳 Pericarpium Papaveris) (Fig.12), Bing Lang (槟榔 Semen Arecae), and Sha Ren (砂仁 Fructus Amomi). This demonstrates that foreign medicines have long entered China and have long become assimilated for use in Chinese medicine.5 Animal products such as Wu Ling Zhi (五灵脂 Faeces Trogopterori) and Lu Bian (鹿鞭 Cervi Testis et Penis) can be seen in the collection. One approximately 2.5 cm-sized piece of Lu Bian was surrounded by unidentifiable plant material that had broken down into powder. This suggests that some plant material was originally used to facilitate the storage of animal products, presumably by preventing insect damage.Figure 11: Ru Xiang (乳香 Olibanum)Figure 12: Ying Su Qiao (罂粟壳 Pericarpium Papaveris)In the context of minerals, one oval-shaped specimen of Yang Qi Shi (阳起石Actinolitum) was striking. Its texture was smooth and moist, with fiberglass shards that sparkle. Dried nuts such as chestnuts, hazelnuts, walnuts, and pine nuts are often sold through the same commercial channels as Chinese herbal medicines. One walnut specimen had been sliced horizontally with its shell intact, as though it had been made into a specially prepared specimen; this was unique within the collection. A number of items featured marks that were indicative of medicinal processing, such as the smoke-processed Wu Mei (乌梅 Fructus Mume) and stir-fried Bi Ma Zi (蓖麻子 Semen Ricini). Additional preparation techniques can be observed by the cutting methods used to produce thin slices or strips for the herbs Zhi Shi, Hou Po (厚朴 Cortex Magnoliae Officinalis), Gan Cao (甘草 Radix et Rhizoma Glycyrrhizae), Chen Pi (陈皮 Pericarpium Citri Reticulatae), and Bing Lang. The color of many specimens has changed owing to prolonged storage over the past 300 years. Insect damage and oxidation have caused many specimens to become dark brown. The latex threads seen in Du Zhong (杜仲 Cortex Eucommiae) are no longer present. Most specimens no longer had an aroma, with the exception of one specimen of chili pepper that was still spicy and irritating to the nose. The shape of the chili pepper differed from the long, thin chili that is common in China today, but its characteristic seeds could still be clearly seen. Chili entered China during the Ming dynasty, but the precise shape of these early chilies remains unknown. Owing to limitations of time and equipment, a number of species could not be identified at that time. For example, one box labeled Dang Gui (当归 Radix Angelicae Sinensis) did not contain any medicinal material. In other cases, the external features of the material were not adequately intact for clear identification, as in the case of Ying Shi (营实 Fructus Rosae Rugosae), Qing Guo (青果 Fructus Canarii), He Shi (鹤虱 Fructus Carpesii), Rou Gui (肉桂 Cortex Cinnamomi), Xuan Shen (玄参 Radix Scrophulariae), Mao Dong Qing (毛冬青 Radix Ilex Pubescens), and Ji Dan Guo (鸡蛋果 Passiflora edulis Sims). Additionally, some specimens such as camphor wood from Japan and hemp cloth-like material from Thailand require further verification before they can be identified. Voucher specimens are the cornerstone of modern scientific research in the discipline of authentication, and they also provide strong evidence helpful in researching the medicinal materials used in ancient times. At present, known collections of Chinese medicinal specimens include nine medicinal spices that were unearthed at the Mawangdui tombs in Changsha, as well as sixty varieties of Chinese medicines that have been stored in Japan since the Tang dynasty in the Shosoin storehouse. Additional collections include aromatic woods recovered from a Song-dynasty shipwreck site in Quanzhou, Chinese medicinal specimens with a history of more than one thousand years at the Liao Shangjing Museum at Balin Left Banner in Inner Mongolia, and a number of Qing-dynasty medicinal materials that were preserved in the Forbidden City in Beijing. These treasured specimens offer firsthand evidence that cannot be replaced by references in the literature alone. The specimens in the British Natural History Museum have survived the waves of the sea and the fires of dry land, making them all the more precious for discovery and identification. Upon investigation, it is apparent that the British Museum and the National Library are valuable resources for early botanical illustrations, as well as medical classics from both the East and the West. This area is worthy of deep investigation, discussion, research, and development, and represents a rich resource for the history of natural sciences that must be approached via a multinational, multidisciplinary effort. Our research is just beginning, and we will continue in this direction. Funding None. Ethical approval This study does not contain any studies with human or animal subjects performed by any of the authors. Author contributions Zhong-Zhen Zhao wrote and reviewed the article. Eric Brand translated and revised the article. Conflicts of interest The authors declare no financial or other conflicts of interest. Zhong-Zhen Zhao is an editorial board member of Chinese Medicine and Culture. The article was subject to the journal's standard procedures, with peer review handled independently of this editorial board member and his research group.