BLACKMAN : THE SPERMATOGENESIS OF SCOLOPENDRA. 71 



of this structure appear the nucleus is still without a definite membrane, 

 and throughout the whole of the early development of the acrosonie it 

 decreases in size as the acrosome grows. It is possible that the material 

 which acts as a solvent for the archoplasmic spherules is derived from the 

 hyaloplasmic portion of the nucleus, rather than from the cytoplasm, as 

 these vesicles are always very near to, if not actually in contact with, 

 the nucleus (Figs. 95, 9G, 98), aud their contents show the same lack of 

 stainability which characterizes the nuclear sap. However, it cannot 

 be doubted that the archoplasm is the chief contributor in the formation 

 of the acrosome. 



With the change in the chemical nature of the chromatin (Fig. 99), 

 the nucleus decreases considerably in size and at the same time under- 

 goes a change of form (Figs. 98-100). From the almost spherical 

 condition it passes at first into an irregular and then into a slightly 

 elongated form (Figs. 96, 97). Afterwards the posterior face becomes 

 more or less flattened, until in some cases (Fig. 98) the nucleus appears 

 truncate. This condition is succeeded by one in which the whole nucleus 

 becomes much more elongated (Fig. 102). The further changes in the 

 nucleus will be described later. 



Returning, now, to a further consideration of the axial filament during 

 the elongation of the spermatid, the question naturally arises, where 

 does the material for its growth come from 1 It has been shown that in 

 all probability the material for the formation of the proximal portion of 

 this structure is obtained from the archoplasm, for at first it is com- 

 pletely enveloped in the mass of this substance which likewise surrounds 

 the centrosome. Later, however, when it has outgrown this visible ac- 

 cumulation of archoplasm, it probably grows at the expense of that por- 

 tion which is still disseminated through the cytoplasm. But as the axial 

 filament continues to increase in length, the archoplasm in solution in 

 the cytoplasm becomes diminished, as is indicated by the increasing trans- 

 parency of the inter-reticular areas (Figs. 92-94). 



About this time, which coincides with the beginning of the elongation 

 of the cell and with the detachment of parts of the archoplasm to form 

 the fundaments of the acrosome, other portions of the archoplasm break 

 off from the mass surrounding the centrosome and migrate in an opposite 

 direction along the axial filament. Various stages in this process are 

 shown in Figures 92-96. In Figure 92 one of these archoplasmic 

 masses is just leaving the central mass and beginning its migration 

 along the filament. In Figure 93 two such bodies have broken off and 

 a third is in process of forming. In Figure 94 several of these have 



