Resumen por el autor, A. R. Ringoen.Los leucocitos cebados en el conejillo de Indias adulto bajo condiciones experimentales.Las preparaciones del tejido subcutineo de 10s conejillos usados en 10s experimentos demuestran que 10s leucocitos cebados de este mamffero duplican de mod0 sorprendente la respuesta de 10s leucocitos polimorfonucleares en su reacci6n positiva hacia las inyecciones subcutheas de clara de huevo. Bajo sus nuevas condiciones de medio ambiente, 10s leucocitos cebados pueden funcionar como fagocitos, per0 pronto experimentan ripida destrucci6n. Esta destrucci6n ripida en el tejido subcutineo no puede explicarse fhcilmente, en vista de la circunstancia de que semejante tejido en el conejo contiene normalmente leucocitos cebados, y a diferencia de lo que ocurre en el conejillo de Indias, no exhiben signos de degeneraci6n. La sangre refleja 10s efectos de las inyecciones de clara de huevo, exhibiendo puntuaci6n basoffica y policromatofilia-f en6menos que indican toxicidad por parte de dicha substancia. El efecto sobre la m6dula 6sea se expresa morfol6gicamente en el aumento del desarrollo de 10s leucocitos cebados. La tremenda actividad por parte de la m6dula osea es una prueba substancial de la creencia de que 10s leucocitos cebados del tejido subcutdneo son de origen mielcide, aun cuando la sangre no exhibe leucocitosis de cblulas cebadas. El desarrollo de 10s leucocitos cebados bajo condiciones experimentales demuestra que en el conejillo de Indias 10s grinulos de dichas c6lulas atraviesan un ligero proceso evolutivo. Los mielocitos cebados se tranforman I en 10s leucocitos correspondientes, 10s cuales son idhticos a 10s que existen en la medula 6sea del animal normal no inyectado. Los resultados de estos estudios experimentales confirman la opini6n de que 10s leucocitos cebados del cone,iillo de Indias represent an verdaderos granulocitos (Weidenreich, Maximow, Downey y otros) y, ademis, que poseen propiedades fagociticas y quimothticas.

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The investigations of Maximow have shown that in mammals the connective tissue mast cells are very different from the mast cells of the blood. Maximow and Weidenreich believe that the only feature which the two types of cells have in common ii the presence of basophilic granules in the cytoplasm, which stain metachromatically with basic aniline dyes. The two types of cells, however, represent independent lines of leucocyte differentiation and development, with their own peculiar nuclei and granules.Maximow ('06) found histogenous mast cells in all the mammals he investigated, even in the rabbit where most investigators have failed. He calls attention to the fact, that where there are relatively few histogenous mast cells, the deficiency is made up by increased numbers of haematogenous mast cells, and vice versa. That such a close compensatory relationship exists between the two types of cells is shown very well in the adult rabbit, there being comparatively few histogenous mast cells, but numerous mast leucocytes.Within the past few years the origin of the haematogenous mast leucocyte has been the subject of considerable haematological investigation. The earlier investigators, including Ehrlich, assumed that mast leucocytes were represented in the bonemarrow by certain characteristic myelocytes and evolved like the other granular cells. Weidenreich, however, has recently shown that this is not the case with the human mast leucocyte. He believes that human mast leucocytes are formed from de- 233

FIVE PLATES (THIRTEEN FIGURES)Keyes and Potter ('34) apparently were the first investigators to observe that in female pigeons many specimens exhibit solid bones, whereas male subjects uniformly have marrow-filled bones. The bone conditions of the female birds were found t o correlate most closely with those of the ovary. When the follicles were 2 mm. or less in diameter, the femoral shafts showed large marrow cavities. Spicules of bone partially invaded the bone marrow in birds in which the follicles were more than 4.5 mm. in diameter and bony spicules filled the medullary cavities when the follicles were of 10 mm. or more in diameter.Bloom, Bloom and McLean's ('41) investigation, on the medullary bone changes during the reproductive cycle, is also based on the study of female pigeons. Intense bone formation was observed during the preovulatory period, while the follicles (ova) were maturing within the gonad. According to Riddle, Rauch and Smith ('44), low grades of ossification in the pigeon usually occur when the ovarian follicles are of 2.8 mm. to 4.0 mm. in diameter, and this is accompanied "by a very marked increase in the weight of the oviduct; the latter fact indicates an increased production of estrogen by the bird." The authors assert that complete ossification usually takes place when, or soon after, the ova (follicles) attain a diameter of 9 to 10 mm. The present investigation relates to the conditions encountered in English sparrows and Bobwhite quail. A preliminary account on the findings in the latter has been previously made (Ringoen, '40). The present paper reports further studies, again utilizing the same species as subject material. MATERIALS AND METHODSThe sparrows for study were trapped in nature, throughout all seasons of the year, and kept in cages in the animal room of the Zoology building until sacrificed later. Although it was known from 'Aided by a grant from the Graduate School of the University of Minnesota. 265