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It is known that plague epidemics and pandemics spread both by sea and by land. However, in the 16th century an entire "hidden face" of the continent was discovered and opened thanks to the Portuguese. It is noteworthy that just as Francis I or the Dutch, Yersinia pestis did not respect the longitudinal limits set out by the treaties of Tordessillas and Saragossa. Even before the arrival of Vasco de Gama in Goa and all the way to the settling of the Moluques in Macao, Canton and Kagoshima, one can follow the progression of at least ten or so epidemics against a general epidemic back drop, thanks especially to the works of Jose de Vasconcellos e Menezes as well as some others. Scurvy was, as far as plague was concerned, a regulating factor, at least to a certain extent.

Raw extracts from one Polynesian, frequently ciguatera-inducing fish were submitted to fractional distillation by means of a chromatographic process using a silicic acid column. Three out of the seven fractions split this way exhibited either anticholinesterasic properties, or directly toxic properties at the muscle-cell level: fraction 5, which is not antagonized by atropine, presumably accounts for this direct action, as it competes with calcium at membrane sites. Fraction 6 appears to be more specially responsible for the anticholinesterasic action. It revealed a quaternary ammonium ion in its 6-2 sub-fraction. Fraction 7 shows the same properties as fraction 6, but on a smaller scale.

The presence of 3,4-benzopyrene is reported in samples of water and sediments from three briny ponds free from pollution of exogenous origin belonging to three different atolls of Polynesia. The synthesis of this hydrocarbon seems to be dependent on the presence of abundant phytoplancton and of bacterial flora.

The appearance of acute eczematous dermatitis in fishermen from the estuary of the Seine, about which the responsibility of Alcyonidium gelatinosum (L.) is still under discussion, led us to estimate the ability of this Bryozoa to induce cutaneous responses of delayed hypersensitivity. Intradermal tests carried out in guinea-pigs after subcutaneous, respiratory or percutaneous sensitization, gave evidence of a clear allergenic ability of this alcyonelline. The deposit of the biological product on normal skin during four consecutive days is enough to induce strong responses of delayed hypersensitivity. This experimental study needs further investigations in which the possible existence of anaphylactic reactions should be confirmed.

Two fractions of ciguatoxic extracts were isolated by chromatography. The first showed anticholinesterasic properties, while the other acted directly on the muscular fibre. These findings were histoenzymologically confirmed. Controls with non-toxic extracts of fishes from the coral benthos reinforce the theory of the ecological origins of ciguatoxins.

The use of histo-enzymological techniques for visualizing the cholinesterasic spots on the motory plate is turned to account by the authors to point out the inhibition of the cholinesterasic processes, by some fractions of the ciguatoxins at the level of the neuro-mucular synapsis. The results obtained confirm, on one hand, the efficiency of the method to test the anti-cholinesterasic activity of some fractions of the ciguateric extracts, and, on the other hand, enable the establishment of the fact that even clinically non toxic individuals from fishspecies, dwelling in tropical coral biotops, can provoke a slightly marked but real inhibition of the cholinesterases, provided the contact between the fish extract and the neuro-motory plate is long enough in time. This observation reinforces the thesis of the ecological origin of the toxins along the alimentary chain of the reef biocoenosis.