142 J- Moore, 



Prior to the final onset of mitosis in the rat's spermatocytes there 

 is beside the nucleus, and often closely applied to its circumference, a 

 small, irregular, refractive body (or group of bodies) similar, or nearly 

 so, in reactive capacity to the archoplasm (Fig. 3 a), quite constant in 

 appearance, and thus to be perhaps looked upon as an organ of the 

 cell. Of the significance and history of this structure (or these struc- 

 tures) I know nothing; since they disappear as mysteriously as they 

 come during the course of mitosis, and are not reformed in the 

 spermatids. I propose to term this body the Lesser NehenJcernA) 



Division of the spermatocytes. 

 The nuclei of the spermatocytes, when first formed, are intensely 

 chromatic, but as development proceeds the close network of chromatin 

 gradually gives place to a ragged scafiolding of stainable material, and 

 this, when subjected to the action of differentiating dyes, shows a 

 distinct separation into at least two constituents. One of these stains 

 darkly with the essentially nuclear coloration, the other takes more 

 conspicuously the cytoplasmic stain (Pig, 2). Comparison of the suc- 

 cessive stages in the development of the spermatocytes always shows 

 that the affinity of their nuclei for stains that are essentially nuclear 

 is inversely proportional to their progress in development, and this 

 phenomenon is manifest up to the formation of the final chromosomes. 

 During the later stages of their growth a relatively small, but growing 

 and intensely chromatic, particle makes its appearance in the cytoplasm 

 (Figs. 2, 3 6 c). When sections containing cells in the appropriate condi- 

 tions are treated with a mixture of Fuchsin and Methyl-green, and 

 the double stain thus produced is washed out with a solution of 

 Orange G., the chromatic particle assumes the bright red coloration 

 represented in the figures, and is by far the most brilliantly coloured 

 object in the field. There can be no doubt that this body is the 

 chromatic body described by Hermann in the testes of the mouse, 

 and which he supposed to be a dismembered portion of the Nebenkern. 



^) I should have simply adopted the name Nebenkein , as this term , in the 

 German literature, stands as a refuge for structures destitute of homolog-y, but for 

 the fact that the archoplasm, the best known Nebenkern, has taken it to itself in 

 much of the more recent literature. 



