Doncaster Microscopical and General Scientific Society
A meeting of the society was held at the guild Hall on Wednesday evening, November 26th, Mr. J. G. Walker, president, in the chair.
Messrs. T. L. Atkinson, E. G. Bayford, and Godfrey Crawshaw were elected members of the society.
Mr. H. H. Corbett, M.R.C.S., read a paper on “The First Principles of Entomology,”
In giving a short historical sketch of the science, the lecturer alluded to the interest taken in it by Aristotle, Pliny, Virgil, and stated that little further was done until the time of Linnaeus, in the 17th century. The system of classification adopted by this great naturalist has undergone considerable alteration. Several of his orders of Insects included what are now placed amongst animals, such as spiders, scorpions, woodlice, centipedes, crabs, etc.
The lecturer then gave a definition of an insect and a careful general description of its anatomy, noting the number of rings or segments of which the body is composed, and enumerating the appendages of each portion. One forms the head, three the thorax to which are attached the legs and wings, when they are present, and the remaining nine form the abdomen. The internal anatomy of an insect consists of a blood circulatory system; a respiratory system – the air passing through apertures (spiracles) at the sides of the abdomen into tubes (tracheae) which ramify through the whole of the body; a digestive system, consisting of alimentary canal, liver, etc.; a nervous system, made up of a double chain of ganglia and fibres, comparable to a sympathetic system in vertebrates. It is doubtful whether insects feel pain, and, indeed, it may be said that a wasp, divided by a pair of scissors is, perhaps, happier than the whole wasp, because it can eat for ever and never get full.
An insect may be briefly divided into three portions, head, thorax, and abdomen, and having six legs and generally two or four wings. Insects, like all other animals, begin life as an egg, which when hatched become larvae or grubs. The larvae becomes pupae and the pupae develop into perfect insects or imago’s. The three stages may be very similar one to another, the change being a very gradual one, or they may differ widely and the change be sudden; in the former case the metamorphosis is said to be incomplete, in the later complete. The essential difference between the three consist in the power of reproduction being limited to the perfect insect. Probably, the earliest form of insect was an aquatic species, allied to the crustaceaus and the myriapods, the nearest approach to such a type being found in Lepisma (sugar louse) or in some of the orthoptera.
A classification of insects, based upon a supposed archaic system, is impracticable, and failing this the alternative is taken of classification by type. In explanation of the meaning of the later, a group of moths was exhibited, showing the connections one with another. A type of the Group Noctuinae being placed in the centre and radiating from it, other noctuinas which approached in character to other groups.
The lecturer then gave a short description of a type of each of the principal order of insects and also alluded to the alteration of generations in aphids.
A discussion of much interest followed, and the meeting closed with a cordial vote of thanks to the lecturer.