1) The Subcostales were always present in man and located on the inner surface of the thoracic wall near the spine. In contrast to this, they usually were absent in monkey and only rarely present. It was found In only one case of Macaca irus. Accordingly, the following summary is one in man. 2) In man these muscles were present on both sides of the body on each side of the spine. The average number of muscles in each case was about five but individual variations are large. These muscles were located largely in the upper and lower thoracic regions with few in the mid-thoracic region. These muscles could b e classified into six types according to the origin, insertion and number of intercostal spaces occupied by the muscle. Most common was that type in which the muscle crossed over one rib to occupy two intercostal spaces. 3) The relationship of this muscle to the intercostal muscle showed that, in the intercostal space where the intercostal nerve to this muscle is located, the lower surface of this muscle was usually fused with and inseparable from the Intercostalis internus in the deeper (outer) layer. In the other intercostal space, however, there was no adhesion with the underlying Intercostalis internus. Therefore, this muscle appears to be part of the Intercostalis internus in the intercostal space where the innervating nerve is located. In such instances, the innervating nerve which sends a branch to this muscle passed lateralward beneath the lower surface of this muscle. In addition, there were rare cases in which this muscle presumably was part of the Intercostalis intermedius, particularly among muscles in the highest or lowest intercostal space that were located in the area close to the spine. In such cases, the intercostal nerve which sends off the nerve to this muscle passed across the upper surface of this muscle. 4) The nerve supply to this muscle was by a branch from the intercostal nerve. This is the same branch that supplies the Intercostales internus and intermedius. Regardless of the length of the muscle, the nerve supply was always by one intercostal nerve with no contribution by a intercostal nerve of any other segment so that it is a monosegmental muscle. Among the m ost common type of muscle, that is cases in which the muscle occupied two intercostal spaces, the level of the fifth rib was a boundary in which muscles located in the upper half above this level tended to be innervated by the intercostal nerve in the lower intercostal space while those in the lower half were innervated by the intercostal nerve in the upper intercostal space. No definite rule could be established for muscles that occupied three intercostal spaces. 5) In view of the relationship of this muscle to the intercostal muscle and the condition of nerve supply, this muscle as a rule appears to belong to the same system as the Intercostalis internus or in rare cases the Intercostalis intermedius. A part of the Intercostalis internus of in rare cases the Intercostalis intermedius, instead of in serting into the adjacent rib, had presumably extended further to seek insertion into some other rib. Furthermore, this sepa r ation, development and extension of the muscle appears in the upper thoracic region to be mostly in the direction from the lower rib toward the upper rib while in the lower thoracic region it is from the upper rib toward the lower rib. 6) This muscle was classified into a number of types according to the number of intercostal spaces occupied by the muscle, but this also can be regarded to indicate the course of separation, extension and development of this muscle from the intercostal muscle.

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The embryonic and postem bryonic development of the hamster ultimobranchial body was studied in relation to the differentiation of parafollicular cells. The results were as follows: The embryonic development is divisible into 4 s tages: 1. branchial pouch stage (9 to 10 days of gestation)a stratified epithelial pocket communicating with the pharynx in the form of the 4th branchial pouch,2. separation stage (11 days)an independent stratified epithelial cyst, without communicating to the pharynx,3. incorporation stage (12 to 13 days)its inclusion within the thyroid lobe, beginning production of epithelial cell masses from the cyst and subsequent fusion with thyroid primordial tissue and 4. dissolution stage (14 to 15 days) contains increased , development of the epithelial cell masses. This stage continues towards postnatal life, being further dissolved into different components as main and accessory cysts with or witho ut 'ciliated cells and goblet cells. The parafollicular tell s differentiate from the epithelial cell masses. The epithelial cells of the epithelial cell masses become precursorsthose with a large nucleus and a large cell body and are typical in ,appearance for the first time on three days after birth and grow in size towards puberty.

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A new histochemical staining meth o d called cytochrome c adjective reaction was devised for the demonstration of acid mucopolysaccharide from the experimental results that cytochrome c purified from horse heart intensely oxidizes leucopatent blue-H2O2 solution and changes it to original deep blue. Tissue sections in this reaction were first treated with 0.1% aqueous solution of cytochrome c, washed well in distilled water or formate buffer at pH 3.0 (in electron microscopy), then stained with a peroxidase reagent such as leucopatent blue or benzidine solution containing hydrogen peroxide. This reaction selectively stained the matrix of cartilage, substantia propria of cornea and granules of tissue mast cells, while tissues containing carboxylated mucopolysaccharides remained unstained. Thus, this technique furnishes a method for localization of sulphated mucopolysaccharides such as chondroitin sulphate, keratan sulphate and heparin, as shown in experimental results obtained by the comp lex formation in vitro and in tissue sections of cytochrome c with acid mucopolysaccharide, by paper electrophoresis of the complex, and by enzymatic digestion tests in tissue sections. Further, the mechanism of this c y tochrome c adjective reaction is postulated to be a complex formation of an amino group of cytochrome c with a sulphate group of acid mucopolysaccharides, whic h can be clearly demonstrated by peroxidase reagents at the level of light and electron microscopy. Never t h eless, it is desirable to combine more sensitive reagents with cytochrome c to detect all acid mucopolysaccharides. Furthermore, the factors that disturb the staining of carboxylated mucopolysaccharides in this reaction still remain unanswered. We would like to thank Dr. Kiy o shi Sekita, Professor of Biochemistry, School of Medicine, Keio University for helpful suggestions and encouragement. We are very grateful to Dr. Hiroshi Kushida and Mr. Kunio Fujita in whose laboratory part of this work was planned and performed.

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