616 ROBERT H. BOWEN 



smoothed out (tigs. 15 and 16), and all traces of its original 

 composition are lost. 



In Callosamia the whole acrosome tends to stain darkly 

 during the period of formation, a phenomenon whicli I have 

 also noted in Hemiptera and in Ceuthophilus when the 

 staining is not perfect. This is presumably the source of the 

 similar condition in Callosamia, for when the Golgi bodies 

 have all cleared away the acrosome is clearly constructed on 

 the same. ])Ian as in Pygaera. The difference in size is, 

 how^ever, astonishing, for in Callosamia the whole acrosome 

 is exceedingly small and inconspicuous (figs. 50 and 51). 

 Nevertheless, it is differentiated into a vesicular and a granular 

 part exactly as in Pygaera . The granule tends to be slightly 

 elongate rather than rounded in the stage at which I have first 

 succeeded in differentiating it. Earlier stages (figs. 46 and 48) 

 show very clearly the relation of the (lolgi bodies to the forming 

 acrosome, but I have not been able to make out their individual 

 contributions, which are presumably very minute. Fig. 49 

 shows an interesting case in which the last Golgi body is just 

 on the point of separating from the acrosome. In this case the 

 Golgi body appears to be a fusion product of several smaller 

 Golgi bodies. 



The interpretation which has here been given furnishes, 

 it seems to me, a complete explanation of Gatenby's results, 

 and brings the lepidopteran acrosome into harmony with the 

 conditions as we now know them to exist in many other 

 animals. According to the idea which I have developed each 

 Golgi body in a lepidopteran spermatid would be an acroblast 

 on a small scale, and the formation of the acrosome is thus 

 a multiple process. In its essential outlines it is, however, 

 clearer than in the case of the grasshopper which I have 

 described in another place (Bowen, 192'2 d). For the relation 

 of this type of acrosome formation to more familiar cases in 

 other aiiimals the reader is referred to my paper on the acrosome, 

 in which I have tried to bring the w^hole series of known facts 

 under a common view-point (Bowen, 1922 e). 



Gatenbv's account leaves the further historv of the acrosome 



