^22 FOOT AND STROBELL. [Vol. XVII. 



acetic are especially favorable for its study/ as they cause it 

 to aggregate into masses, thus producing the sharpest contrast 

 between the red and the blue. In chromo-acetic preparations, 

 on the contrary, the distribution of the archoplasm is much 

 more equal throughout the cytoplasm (p. 7). TJie process (of 

 staining) must be carefully watched wider the microscope, for 

 the lithium carmine ijt both the spindle fibers and cytoplasmic 

 network may be replaced by the Lyojis blue " (p. 4).^ 



Photos 1-23, PL XLI, show successive stages of the growth 

 and the varying distribution of the yolk-nucleus, from its first 

 appearance in the tiny cells of the ovary until its final dis- 

 tribution throughout the cytoplasm of the large oocytes, first 

 order, at the distal end of the ovary. During all these stages 

 it is morphologically an accumulation of granules. When 

 the granules are scattered through the cytoplasm they are 

 very difficult to demonstrate ; but when they are aggregated 

 into more or less definite masses they can be readily differen- 

 tiated. We interpret Photos 51-59, PI XLIII, as showing 

 later phases of the same granular substance. In Photo 5 5 part 

 of it is aggregated into masses, which resemble the ovarian 

 eggs of Photos 21 and 23, PI. XLI. Through all these stages 

 the substance is morphologically the same (granular) ; but 

 it has not been possible always to reproduce this feature 

 in the prints. These photos (51-59, PI XLIII) show that 

 this substance, which in the younger eggs (51-54) is more 

 evenly scattered through the cytoplasm, aggregates towards the 

 periphery (55-57) as the egg develops, finally leaving the cen- 

 tral part of the egg relatively free from the dark granular 

 substance. This feature is clearly shown in the fifteen serial 

 sections of PI. XLIV (Photos 63-77). We have thirty-three 



1 This point is illustrated in Photo 55, PI. XLIII, and in many photos of an 

 earlier paper (12). 



2 In view of this specific statement of the need of exercising great caution in 

 the use of Lyon's blue, to avoid staining other structures in the cell, it is inter- 

 esting to note Wilson's criticism published in his work on the cell. "To 

 identify as ' archoplasm ' everything that stains with Lyon's blue is indeed a 

 broad use of the term" (31, '96), p. 121. Later this was repeated by one of his 

 pupils. " Foot calls everything in the cell which stains with Lyon's blue, archo- 

 plasm." Calkins (4), p. 728. 



