Laboratory directions in general zoology

Preface

These notes are the outcome of one mimeographed and two printed editions, which have been written for the introductory course in zoology at the University of Missouri. The effort has been made with each revision to better adapt them to the needs of our students and to make corrections where the plan of work or the phraseology had proved unsatisfactory. As will be evident to any one with experience in work of this character, they are unusually full and this will doubtless be a matter of criticism by those who believe that the student should receive as little help as possible in the simpler parts of his laboratory study. The author agrees entirely with this contention and it is the very thing he has attempted in the writing of these laboratory directions and in the whole organization of his work in the teaching of general zoology. With this end in view, the work of the course is so planned that some laboratory work shall precede any text-book or lecture study upon a given form. Where the student begins his study of each animal with laboratory observation, it will be found that too brief directions result in his being constantly in need of help from the instructor. In such a plan of work he needs notes which will offer adequate direction and at the same time present a carefully studied attempt to make him determine for himself all the points which experience shows are made out by the better students. If, in addition, the instructors in a laboratory will try never to answer any question the student can be fairly expected to answer for himself, confining their attention to setting him right when he is on the wrong track with his material or has misunderstood the directions, and will, on 'the other hand, spend most of their time in explaining the broader aspects of the facts the student sees and in responding quickly to the kind of questions he asks when doing understandingly the work called for, the author believes that the.

Ill maximum of efficiency in laboratory instruction will be obtained, and these notes have gradually developed in conformity with this method of instruction. This procedure should, of course, not be pushed to the extreme of having all the laboratory work come first, because the student should have another chance at the material after his lecture and text-book study have given him a broader appreciation of what he can see in the laboratory, the ideal plan being to have the latter part of the laboratory study follow the main portion of the lecture and text-book assignments. When this plan is adopted, it has been our experience at the University of Missouri that students can be trained to work independently with the directions here given, while the advantage for lecture and text-book work lies in the fact that the student understands much more readily what he reads or hears after he has seen something of it at first hand. Thus a good deal of time may be saved, particularly in lectures, which, when they precede any first hand knowledge, often labor to explain what could be much better seen and mastered by the student without any preliminaries. Most of the work has been written de novo for this course although the author has made no attempt at originality in many of the minor points, which have been accumulated from many different sources and sifted out until they represent the result of his teaching experience. In the original mimeographed edition, the notes on a number of forms were largely a modification of the Laboratory Directions in General Zoology by Professor E. A. Andrews of the Johns Hopkins University, to whom more than to any other one man the author feels indebted for his present habits of thought as a laboratory teacher. Very little now remains which would connect what is here given with the notes by Professor Andrews. In the section on the Earthworm, however, there are a number of paragraphs which have survived and perhaps a sentence here and there in the notes on the Frog, the Unicellular Forms and the Hydra. For permission to use these as they stand in the present edition, which is copyrighted and placed on general sale, I am indebted to Professor Andrews. The greater part of the notes were, however, first written and have since been revised

IV directly from the material and may be regarded as an outcome of the laboratory teaching of General Zoology at the University of Missouri during the past ten years. I have to thank my colleagues, George Lefevre, G. W. Tannreuther, and G. S. Dodds, and our assistants who, from year to year, have helped with each revision to eliminate the most obvious defects in phraseology and method.

Winterton C. Curtis.

January 1, 1912.

Preface To The Present Edition

The present edition has been revised in the light of further experience at the University of Missouri and of suggestions from other institutions in which the directions have been used. Some additions have been made with a view to making the work more adaptable, particularly in courses where the plan for introductory work in zoology includes a somewhat wider range of forms. In this connection, the scope of the lecture and text-book work in General Zoology as given at the University of Missouri may well be stated. The course is one for five hours credit during one semester. The schedule calls for two lecture periods of one hour and three laboratory periods of two hours each, with reasonable latitude for the individual instructor in the substitution of quiz or lecture work for some of the laboratory periods. The plan of the laboratory work in relation to the entire course of study will be understood by the following outline:

I. Representative Forms of Animal Life.

(Studied with reference to their structure, physiological processes and life-cycles and as living animals rather than as representatives of a particular phylum).

(a) The Frog, as a familiar form.

(b) Unicellular Forms, to illustrate the basic phenomena of living things.

(c) The Hydra, as a simple metazoon.

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(d) The Earthworm, Crayfish or Mussel, as a complex metazoon of distinctly different organization from the more familiar vertebrates. Only one of these is usually studied in full as outlined.

II. The Ontogenetic Development of Animals.

(a) Cell Division, Maturation, etc.

(b) Cleavage and Formation of the Germ-layers.

(c) Life-cycle of Amphibia.

(d) Embryology of Frog and Chick.

III. Ecology, Behavior, Intelligence, etc.

(a) The Insects.

(b) The Parasitic Worms.

IV. The Classification of Animals and their Phylogenetic Development.

(a) Brief Examination of the Principal Phyla.

V. Organic Evolution, lectures and demonstrations only.

These five main topics, of course, receive emphasis throughout the work, but they are more extensively developed in connection with the laboratory matter above indicated. The course, therefore, deals with a rather limited list of animals, and while the student is given an opportunity to form some conception of the more important phyla there is no intention of taking him from end to end of the animal kingdom as is sometimes done in courses entitled General Zoology. The aim is rather to present the fundamental phenomena of living matter as illustrated by representative forms of animal life.

At the request of Professor W. M. Smallwood of Syracuse University, notes are added upon the bony fish and the snail. These have been placed in an appendix as they do not logically belong at any place in the scheme of the course as here outlined. For these notes and for the outline of work upon the arteries of the frog, I have to thank Professor Smallwood and the staff at Syracuse University.

Winterton C. Curtis.

University of Missouri,

September 1, 1913.

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