DEATH-WATCH, a popular name given to insects of two distinct families which burrow and live in old furniture, and pro duce a mysterious "ticking" sound vulgarly supposed to foretell the death of an inmate of the house. The name is often applied to two small beetles Xestobium rufovillosum and Anobium punc tatum (fam. Anobiidae) but belongs more properly to the former insect. The sound is a sexual call, and is produced by the beetle striking the front of the head upon the surface upon which it is standing. Certain book-lice (order Psocoptera) are sometimes known as lesser "death-watches," but the ability of such minute soft insects to produce audible sound is doubtful. The names Atropos pulsatoria and Troctes divinatorius, given to two of the common species, bear witness to the superstition regarding the fateful significance of the sound.
De Bary will be remembered as the founder of modern mycol ogy, a science which he revolutionized by his celebrated Morphol ogie and Fhysiologie d. Pilze, etc., of 1866. His apprecia tion of the real significance of symbiosis and the dual nature of lichens is one of his most striking achievements. It is as an investi gator of the then mysterious Fungi, however, that de Bary stands out. He not only laid bare the complex facts of the life-history of many forms; e.g., the Ustilagineae, Peronosporeae, Uredineae and many Ascomycetes, but insisted on the necessity of tracing the evolution of each organism from spore to spore. One of his most fruitful discoveries was the true meaning of infection as a morpho logical and physiological process, which he traced in thora, Cystopus, Puccinia and other Fungi, and thereby demon strated the significance of parasitism. He showed wherein lay the essential differences between a parasite and a saprophyte.
These researches led to the explanation of epidemic diseases, de Bary's contributions to which are well seen in his classical work on the potato disease in 1861. They also led to his discov ery of lieteroecisnn (or inetoecism) in the Uredineae, the truth of which he demonstrated in wheat rust experimentally (1863) . He described the phenomena of sexuality in Peronosporeae and Ascomycetes—Eurotieum, Erysiphe, Peziza, etc., and established the existence of parthenogenesis and apogamy on a firm basis. He did much work on the Chytridieae, Ustilagineae, Exoasceae and Phalloideae, as well as on the Myxomycetes ; he contributed to algology in his monograph on the Conjugatae (1858), and investi gated Nostocaceae (1863), Chara (1871), Acetabularia (1869), etc. In 1877 appeared his Comparative Anatomy of Ferns and Phanerogams, and in 1885 his Lectures on Bacteria (Eng. trans. 1887).
Memoirs of de Bary's life will be found in Bot. Centralbl. (1888), xxxiv. 93, by Wilhelm ; Ber. d. d. bot. Ges. vol. vi. (1888) p.
by Reess, each with a list of his works; Bot. Zeitung (1889), vol. xlvii. No. 3, by Graf zu Soems-Laubach.