_ Wa Leesa esas ny 2 MEP OOrEEN ILE Che mE eg ENDOSYHSIOSE der Tic Yerlace Birichauger. 2 f oe te 66.55 (ehoth). This indispensable revision sucsecds the versione issued in 1921 and 193c, It Will surely preserve its long held status as the definitive review of its field and a3 an inspiration for the languishing craft of comprehensive monography, The present edition is slightly shorter than the second, owing largely tc the contracted treatment of algel symbioses in accord with the virtual neglect of this field in the interval, The text is thus most fully concerned with the symbioses of intracelluler microorganions in insects, This topic has hitherto been the subject almost exclusively of descriptive, morphological research, but the fragments of exe perimental studies on the physiology of the symbionts and mutual relationships with the host are extensively discugsed. More recently, many geneticists have awakened to the pertinence of the many symbioses that are perpetuated in heredity and, con versely, have made their own contributions te syzbiclozgy (e.g. L'Heritier on sigma- Drosophila: Sonneborn on kappa=Paramecium) but these aspects are not included here. Despite the weighty documentation of Buchner's reviews, some workers have nurtured a persistent skepticiem, inferring instead that the symbionts are merely specialized mitochondria (which recalls the now discredited theory that mitochondria are microbial inclusicns readily cultivable in vitro). If nothing else, the numerous insects that have been artificially cured of their symbionts should smother such doubts,---except that we cannot ignore the startling and uncomfortable fact that green plants can be "cured" just as readily of their chloroplasts by chemotherapy. The most conspicuous failing in this phase of entomological research as been the lack of a microblological cricntation end close heed to Koch's Postulates, which apply no less to symbiology than to its subsidiary field of infectious disease. Presumably for technical reasens, the microsymbionts of the most intimate complexes have not teen grown in vitro, tut if vould be more accurate to insist that no cone vincing evidence has usually been foruerded thet the isolated microbes inhered in the symbiosis, The potentizl usefulness of the aposymbiotic insect as a specific criterion for such claims, as well es for the general application of the symbiosis concept, by virtue of reinfecticn experiments has not been adequately emphasized, though re~ and crosssinfections have been recorded for a few insects whose symbionts are readily cultivated (Rhodninus prolixiit; Lesioderma serricorne). in vitro culti- vation of the symbionts would not be obligatory in the first instance and the ree. infection test should thus guide the development of the technique for their identi« fication, maintenance and finally artificial cultivation. The outcome for this controversy predicted by this reviewer is not the unmitigated defeat of the mitochondrial at the hands of the microbial theory for SRBEBQ chloreplasts ard symbionts but a reconciliation in terms of a unifying concept labelled elsewhere as the plasmid, A work of such profound merit end diligent detail warrants translation to accommodate students for whom German ic not a native tongue, The content, and perhaps the style, of this monograph are wco formideble for casual perusal. by the English- speaking student. Sucha translatien would enrich the teaching of biclosy and stimilate research in symbiclogy more than enough to justify the task, But whatever the language, no serious student of biology can afford to miss en acquaintanceship with this wort:. dy Lederhers hb