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NATURALISTS have long recognised the curious cases oftentimes occurring, of the resemblance between the colour of an animal and its immediate surroundings. It had been supposed that climatic influences, or peculiarities of food, or greater or less access to light, had something to do with these coincidences. Mr. Alfred R. Wallace has shown that the varied phases of these phenomena could not be explained by such agents, and in a paper “On Mimicry and other protective resemblances among Animals,” published in the Westminster Review, July 1867, and since made widely public in his work on “Natural Selection,” he shows that the singular resemblances between the colour of animals and their surroundings are mainly brought about by the protection afforded them through greater concealment. Many very interesting examples are then cited from the Vertebrates and Articulates in support of these views. Briefly may be mentioned, as examples, the almost universal sand colour of those animals inhabiting desert tracts; the white colour of those animals living amid perpetual snows; the resemblance seen again and again between the colour of many insects and the places they frequent. Among the hosts of examples cited by Mr. Wallace as illustrating plainly the views he advances, may be mentioned the many species of Cicindela, or tiger beetle. The common English species, “C. campestris;, frequents grassy banks, and is of a beautiful green colour, while C. maritima, which is found only on sandy sea shores, is of a pale bronzy yellow, so as to be almost invisible.” He then states that a great number of species found by himself in the Malay Archipelago were similarly protected. “The beautiful Cicindela gloriosa, of a deep velvety green colour, was only taken upon wet mossy stones in the bed of a mountain stream, where it was with difficulty detected. A large brown species (C. heros) was found chiefly on dead leaves in forest paths; and one which was never seen except on the wet mud of salt marshes, was of a glossy olive so exactly the colour of the mud as only to be distinguished when the sun shone, by its shadow. Where the sand beach was coralline and nearly white, I found a very pale Cicindela; wherever it was volcanic and black, a dark species of the same genus was sure to be met with.”

IN NATURE, vol. xxi. p. 350, is a review of my memoir on “The Omori Shell Mounds” by Fredk. V. Dickins. I do not now heed the spirit in which it is written, nor would I deem it worthy of notice did it not occur in the pages of your widely-read magazine. One expects in a reviewer some knowledge of the subject he reviews. Mr. Dickins, by a series of mistakes, betrays his ignorance of the whole matter. The extraordinary blunder he makes regarding the Ainos has already been promptly corrected by a Japanese gentleman residing in London. It is charitable to assume that Mr. Dickins has not lived in Japan, otherwise he would not, in common with so many of his countrymen, commit the wilful blunder of calling the principal city of the empire by its wrong name. On the other hand, it is impossible he could have seen the Omori deposits, otherwise he would not make another blunder by expressing his belief that they have been completely swept away, when in truth but a small portion of them have been removed. He says: "These mounds consist for the most part of shells, little, if at all, distinguishable from what are still found in abundance along the shores of the Gulf of Yedo". Had he taken the trouble to read the memoir he attempted to review he would have seen that all the species occurring in the mounds vary in size, proportion of parts, and relative abundance of individuals from similar species living along the shores to-day. That some species extremely abundant in the mounds are scarcely met within the vicinity, while one species has never been found within 400 miles of Omori; indeed, it belongs to a different zoological province!

MAY I beg to add a few lines to the very interesting correspondence and discussion regarding the immunity of man from insect-stings and snake-bites after successive inoculations. The letter of Dr. Dawson Williams, in NATURE of March 4, calls attention to a certain degree of immunity which obtains among the Norwegians from the stings of the myg, a kind of gnat (probably our midge, Anglo-Saxon mygge). His statements in regard to the degree of immunity varying in different individuals, is quite in accordance with our experience with the mosquito. His pathological description of the effects of the sting of the Norwegian myg would apply most accurately to the sting of the mosquito. We also become more or less immuned from the mosquito poison after much suffering in childhood. The swelling resulting from the mosquito sting will often close the eyes of an infant. In middle age the sting is hardly noticeable. English and Irish people, upon first coming to this country, suffer beyond measure, and often come under the care of a surgeon. It is a curious yet painful sight to see a brawny Englishman presenting the appearance of our young infants under the infliction of these pests. I have two Irish servants, who have been in this country two and seven years respectively. They both tell me that the mosquito bite, as it is called, no longer troubles them, though they were eloquent in the descriptions of their acute sufferings at the outset. More than a quarter of a century ago Dr. J. C. White, a distinguished dermatologist, of Boston, in a communication to the Boston Medical and Surgical Journal, November 9, 1871, discusses the subject fully in a paper entitled, “On the protection acquired by the human skin and other tissues against the action of certain poisons after repeated inoculation.” He not only shows the immunity arising from the repeated stings of mosquitos, but notices a like immunity arising from the domestic pests, Pediculus, Cimex and Pulex. An American recalls his first experiences with the flea in Europe with the same horror that an Englishman remembers the welcome he received from the mosquito in America.