FOUR FIQURESWork upon growth which involves more than the recording of the body weight at certain intervals and the study of the averages obtained from a large number of such weights is of very recent date. It is not surprising, therefore, that the literature contains so few data on the growth of the dry substance. It is true that there are scattered data which have been collected and utilized for comparison in this paper, but with the exception of the central nervous system of the white rat, carefully studied by Donaldson and his associates, there are no extensive records for any species. The available published data usually refer to the water content rather than to the dry substance. Since the relative changes are greater for the dry substance, however, the data in this form are preferable for graphic representation in curves of relative growth. As growth and differentiation proceed, among other changes there is an alteration in the relative amounts of water and of dry substance. It is the purpose of this paper to present some data concerning the nature and extent of this alteration for the skin, skeleton, musculature, viscera and entire body of the albino or white rat during postnatal development.
MATERIAL AND METHODSObservations on 62 white rats (Mus norvegicus albinus) furnish the data presented in this paper. These rats are divided into groups as follows: 12 (6 m.-6 f.) at birth (or within 24 hours); 10 (4 m.-6 f.) at one week; 9 (4 m.-5 f.) at twenty days; 10 (5 m.-5 f.) at six weeks; 9 (5 m . 4 f.) at ten weeks; 10 (5 m.-5 f.) at
TWO FIGURESTo comprehend fully the growth of the body, the following data are required: (1) the growth of the body as a whole; then an analysis to determine (2) the growth of the principal parts; (3) the growth of the various systems; (4) the growth of the individual organs; and finally (5) the growth of the ultimate constituent tissues and cells. Observations upon these various phases of growth in different animals are scattered through the literature, but in no case are they sufficiently complete to afford a comprehensive view of the process of growth in any individual species. In the case of the albino rat, the growth of the body as a whole and of the central nervous system has been carefully studied by Donaldson and his associates. The present paper will give a partial analysis of the growth process in this animal, including the relative growth from birth to maturity in the various constituent parts and systems of the body. A more extensive study of the growth and variation in the individual viscera will be published soon in a separate paper.MATERIAL AND METHODS Ninety-three albino or white rats (Mus norvegicus albinus) were utilized for the present paper. These include 18 newborn (9 males, 9 females); 19 a t 1 week (8 m., 11 f.); 13 at 3 weeks (7 m., 6 f.); 14 a t 6 weeks (6 m., 8 f.) ; 10 a t 10 weeks (5 m., 5 f.) ; 13 a t about 5 months (6 m,7 f.); and 6 at about 1 year (4m.,2f.). They
HIS meeting was called for the purpose of stimulating thinking as to the T possibilities, limitations, and dangers of the so-called "play therapy." The questions raised were based on the experience with "play therapy" at the Institute for Juvenile Research as this experience was described in Dr. Gitelson's paper "Clinical Experience with Play Therapy."' So I should like to see this meeting enter upon a consideration of not merely the technical difficulties involved, which, of course, we must consider, but also the question as to whether or not and under what conditions the so-called "play therapy" can be fitted into the general work of a child guidance clinic.We should also consider whether or not the so-called "play therapy" is a suitable technique for general use in children's agencies, which are otherwise attempting to do social therapy with children.
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