614 DR A. ANSTRUTHER LAWSON ON 
THE ACHROMATIC FIGURE. 
The amount of karyolymph taken into the nucleus during the meiotic growth period, 
seems to remain fairly constant up to the stage when the first mdications of spindle 
formation become visible. A careful study of the nuclear vacuole during this period 
was made, and it was found, after many measurements and calculations, that the nuclear 
vacuole at the stage shown in fig. 24 was more than half the cubical volume of the 
cytoplasm.* Up to this stage there has been no trace of the achromatic figure. The 
nucleus is undoubtedly the most conspicuous part of the cell—the granular cytoplasm 
occupying a narrow zone about it. 
Immediately following this staeg, a very noticeable decrease in the nuclear volume 
takes place. From the conditions shown in fig. 25 it may be clearly seen that the 
amount of karyolymph present is very much less than that in the earlier stage shown 
in fig. 24. It may also be clearly seen that as the nuclear volume decreases, the 
volume occupied by the- cytoplasm apparently increases. The cytoplasmic zone is 
distinctly wider, but its structure is not uniform throughout. That region of the 
cytoplasm immediately surrounding the decreasing nucleus becomes converted into 
a weft of fine delicate threads which appear at places to radiate out for some distance 
from the nuclear membrane. A much more evident decrease in the nuclear volume 
is shown in fig. 28. The volume here is considerably less than half that shown in 
fig. 24. Here also the transformation that occurs in the cytoplasm becomes more 
evident. The fine threads are more numerous and more sharply defined. They appear 
as tufts or sheaves which attenuate as they extend towards the periphery. We have 
here what has been commonly called the multipolar figure, and which has been described { 
for so many of the vascular plants. 
Fig. 25 represents the close of the prophase, where the nuclear membrane is reported 
by other writers to break down and disappear. In another work (Lawson, 19118) I 
have shown that this does not occur in Disporum, Gladiolus, Yucca, and Hedera. 
That there is likewise no collapse of the nuclear membrane in Smilacina is, I think, 
convincingly demonstrated in the series of stages represented in figs. 24, 25, 28, and 29. 
There is no doubt whatever in my mind that, in well-fixed material, the persistence of 
the nuclear membrane may be demonstrated throughout all of these stages. The 
karyolymph, as such, does gradually disappear. It diffuses into the cytoplasm, and | 
am quite convinced that the plasmatic membrane enclosing the karyolymph is functional 
throughout this osmotic transfer. As to the persistence and function of the nuclear 
membrane in this connection, the present investigation on Smilacina confirms in every 
way the conclusions arrived at in the work mentioned above (Lawson, 19118). 
* T should here correct a slight error in my previous paper (LAWSON, 191138). In the latter 1 occasionally used the 
term cell volume when the cytoplasmic volume was really intended. All calculations made in this connection were 
based on the comparison of cytoplasm to nucleus as to cubical volume. 
+ SrrasBurRGER (1895, 1905, 1907), Farmmr (1895, 1905, 1910), Jun (1897), SAaRGant (1897), OsteRHOUT (1897), 
Smirx (1900), Morrmmr (1897, 1898, 1907), Mryaxe (1905), ALLEN (1903, 1905), OveRToN (1905, 1909), GRiGoIRE 
(1908, 1910), Davis (1899, 1909), Bnrans (1904, 1905), Lawson (1898, 1900, 1908). 
