INTERSTITIAL CELLS OF URODELE TESTIS 231 



accordingly. A tangential section of the testis, as in figure 8, 

 shows the lobules in cross-section as several-sided polygons rather 

 than as circles, with the blood vessels occupying spaces where 

 angles of three or more polygons join. The lobules, then, are 

 at this time pyramidal rather than conical, and fit quite closely 

 together, with the result that the interlobular tissue or stroma 

 is subjected to considerable compression, if appearances of 

 fixed material are at all indicative of conditions in the living 

 animal. 



Careful study of the interlobular tissue at this period (July, 

 August) reveals as a rule no cells recognizable as interstitial cells 

 by the usual criteria (i.e., rounded nucleus, polyhedral cell form, 

 plentiful cytoplasm with lipoid or other accumulations). Be- 

 tween the lobules, either as they are cut in cross or longitudinal 

 Section, appear nuclei of an elongated form, (figs. 9 and 25) from 

 25 to 35 At in length, and 5 to 8 m in thickness. From the fact 

 that they are elongated when seen in either of these planes, one 

 would infer that they are of a flattened or disk shape rather than 

 of the true spindle type. This is confirmed by seeing them in a 

 surface view where a lobule chances to be cut tangentially; they 

 then appear either circular or broadly oval with their diameter 

 then approximating the 'lengths' observed for the elongated 

 nuclei. These nuclei contain numerous coarse masses of chroma- 

 tin, which stains more deeply and holds its stain more tenaciously 

 than the chromatin of the germ cells; no nucleoli are apparent. 

 There are no definite cell boundries to be detected between 

 adjacent nuclei. In some cases, a small amount of cytoplasm 

 can be seen at one or both ends of the nucleus; any cytoplasm 

 present must be flattened out between lobules as are the nuclei. 

 And finally, though the lobules themselves may contain consid- 

 erable fat blackened by osmic acid, such blackened droplets 

 are not seen in the interstitial tissue in constant, definite associa- 

 tion with these nuclei; being, indeed, rarely seen there at all. 

 The application of a mitochondrial technique indicates the 

 presence of occasional fine granules in the cytoplasm; but after 

 fixation with Bensley's fluid, and staining with acid fuchsin and 

 methyl green, the larger fuchsinophile granules so numerous in 



