170 EZRA ALLEN 



Nor is it present in the young material in even the pachytene 

 stage, although in the adult tubule it is plainly visible in this stage 

 (fig. 1, P.C.). Its absence in the young material may be due to 

 the fact that the cytosome is not yet fully differentiated when 

 the pachj'tene stage is reached. 



With regard to the nature of the body, Lenhossek objects to 

 identifying it with the nebenkern of the invertebrates on the 

 ground that the germ cells of mammals have no corresponding 

 body. He objects also to classifying it as an attractive sphere, or 

 as archiplasma, since in cell division it does not divide, and each 

 part accompanies a centrosome to its pole, nor does it take part in 

 the formation of the spindle. He says the centrosomes are naked 

 at the poles of the spindle, and that the idiosome (he calls it the 

 Sphdre), remains beside the equatorial plate during the formation 

 of the spindle. 



Wider alles Erwarten . . . lasst sich noch in ungetheiltem 

 Zustande als ein etwas geschrumpfter, noch immer lebhaft farbbarer 

 Korper seitlich neben der Spindel wahrend der ganzen Phase der Spin- 

 delbildung und auch der Aequatorialplatte ; erst mit dem Beginn der 

 Metakinese entzieht sie sich dem Blicke, offenbar durch Auflosung und 

 gleichmassige Vertheilimg ihrer Substanz auf das ganze Cytoplasma 

 der sich theilenden Zelle; muss sich doch ihre Substanz in gleicher 

 Menge in den beiden Theikmgshalften der Zelle finden, da sie sich doch 

 in den Tochterzellen zu je einer neuen Sphare zu construiren hat (pp. 

 243 and 244). 



According to this author, the behavior of the idiosome is the 

 same in both spermatocytes. In the spermatids he thinks its 

 function is to take part in forming the acrosome. 



With two exceptions, my observations agree with Lenhossek 

 on the behavior of this body as far as to the spermatids, after 

 which I have not followed its history. The first exception has 

 already been noted above, viz., that it is not found in the sperma- 

 togonia. The second one is in regard to the staining reaction. 

 I do not find that the body takes the stain more deeply when the 

 chromosomes lie in the equatorial plate,^ with either Flemming or 

 'B-15' fixation, or any stain, and am inclined to think that he 

 confused with this body a chromosome which is late in taking its 

 place, as his figure .shows an irregular body instead of a spherical 



