CYTOPLASMIC INCLUSIONS OF THE GEItM -CELLS. 429 
t^e . mitochondrial matter lias separated fro,m the chromo- 
phobe substance (PL 23, fig. 16, etc.), that the former t again 
becomes distinctly, visible to the eye, and I think that this 
renewed power of resisting acetic acid is caused by some 
definite but unknown change, similar to that already described 
just at the beginning of the growth period. The acetic acid 
acts so violently upon the mitochondrial matter that it pro- 
duces figures like those in Text-fig. l, v after Platner and 
Meves. Here, then, one realises more fully the faulty 
technique introduced into such research by dependence on 
acetic acid, however much reduced, and comparison of the 
figures drawn in this paper from fixatives free from acetic 
acid with those of other observers who have used acetic acid, 
will show that the latters’ drawings are really caricatures 
produced by distortion, and this remark can be readily con- 
firmed by examining material in the fresh and with intra- 
vitam stains. 
There are two periods when the mitochondria of moths 
resist acids : (1) the pre-growth period of the spermatogonium, 
and (2) the period after the formation of the spireme; by 
resist ” I mean to signify the power to resist becoming stained 
and visible, not the power to resist distortion, for Meves’ figures, 
-66, 67, 68, and 69 of Taf. XXV J I (in 1b), show resistance to 
destruction but not to distortion. Acetic acid fixatives seem 
to penetrate so violently that they cause the spireme to 
collapse into a shapeless mass within the chromophobe 
substance. 
Subsequent Fate of the Macro mitosome. 
The spermatozoon was traced up to the stage drawn in 
PI. 23, fig. 17, or PL 24, fig. 23. At this stage the macromi- 
tosome is a distinct spireme, though I do not feel able to say 
whether the coil has free ends or whether it is not so pro- 
vided. 1 However, as spermatozoon formation goes on, the 
macromitosomal spireme appears to become gradually divided 
into two by the impressing of the axial filament upon the 
1 See, however, my paper on the “ Apyrene ” spermatozoa, p. 470. 
VOL. 62, TART 3. NEW SERIES. 30 
