SECONDARY SEXUAL CHARACTERS. 35 



were found. The tubules were enveloped by a circular layer of 

 flat connective tissue cells, which were drawn out into long fibers 

 with flat nuclei. Each tubule was surrounded by several, usually 

 two to five, layers of interstitial cells. Each tubule with the 

 surrounding concentrically arranged interstitial cells formed a 

 group \vhich was often quite sharply separated from neighboring 

 similar groups through lymph vessels or lymph-spaces and blood 

 vessels and accompanying connective tissue strands. In certain 

 places larger blood vessels accompanied by lymph vessels were 

 found in the tissue. Blood capillaries were numerous in certain 

 places. Occasionally a tubule was found adjoining the connec- 

 tive tissue directly, without being separated from the latter by 

 interstitial cells. The character of the interstitial cells varied 

 somewhat in different parts of the organ. Usually they were 

 large polygonal,, partly rounded off or oval cells with a large 

 vesicular nucleus, in which several small nucleoli were generally 

 seen, instead of the one clear nucleus which was so characteristic 

 of the tubule cells. The nucleus in the interstitial cell was not so 

 light and transparent as in the tubule cell. The sizes of the 

 interstitial cells varied. The cytoplasm became finely vacuolar, 

 at first in the periphery. In the center there was still a solid 

 material staining red with eosin. Later the whole cytoplasm 

 became finely vacuolar. This vacuolization was usually accom- 

 panied by a considerable increase in size of the cells. In some 

 cases the vacuoles enlarged still more, the walls separating neigh- 

 boring vacuoles disappeared and irregular cavities became visible 

 in the cells. In those cases the nucleus became irregular and 

 shrank, and when this last stage had been reached, the cell was 

 evidently degenerating. Many finely vacuolar enlarged cells 

 appeared otherwise normal and viable. These finely vacuolar, 

 swollen cells occurred especially around the lymph vessels, or 

 perhaps also around certain blood vessels. We must assume that 

 substances reaching the cells from the circulation were deposited 

 within the cells and caused the vacuolization, the nearness to the 

 source of this substance determining the frequency and intensity 

 with which these changes took place. Under the same condi- 

 tions the accompanying fibrous tissue became edematous. Ap- 

 parently the vacuolization of the interstitial cells and the edema- 



