Nichols, A morphological study of Juniperus communis var. depressa. 227 
from the jacket cells into the egg cell is impossible. They suggest 
that “the jacket cells are glandular or secretory and render the 
storage food of the endosperm soluhle and available for the de- 
veloping egg”. According to Chamberlain (1906), in many 
cycads the egg “receives food material through haustorial pro- 
jections which are in direct contact with the cytoplasm of the 
jacket cells”. But among the Cupresseae the conditions are very 
different from those fonnd in such groups as the Cycadales and 
Abieteae. There each archegonium is completely enveloped by a 
layer of jacket cells, while among the Cupresseae only the outer- 
most archegonia of the group are in contact with the jacket layer. 
Yet, as Lawson (1907b) clearly points out, “the cytoplasm of 
the centrally situated egg cells shows very little difference in the 
character and quantity of food granules from that of the egg cells 
in contact with the jacket cells”. Lawson therefore believes that 
“all food substances carried into the egg are translocated in soluble 
form”, and that “the transference of food substances from egg cell 
to egg cell is the same as that from jacket cell to egg cell”. 
Düring their later history the jacket cells in J. communis, asnoted 
by Noren (1907), are frequently binucleate (fig. 95), and while 
in some cases the nuclear division which gives rise to this con¬ 
dition may be amitotic, as Noren affirms, the frequent presence 
of mitotic figures in the jacket cells as late as the time when the 
proembryo is being developed would indicate that thesenuclei are 
ordinarily produced in the usual manner. 
The nucleoli and pseudonucleoli. — Probably no struc¬ 
tures in plant or animal cells have been the subject of more dis- 
cussion, yet withal are more incompletely understood, than nucleoli. 
The term nucleolus has been applied so indiscriminately by different 
writers to various structures both inside and outside of the nucleus 
that it has come to have a very vague meaning, and a thorough 
comprehension of the different bodies thus designated and of their 
relation to the metabolic activities of the cell would doubtless illu- 
minate many cytological problems which are at present inexplicable. 
It is not the purpose of the writer to enter upon a discussion 
of the nucleolus, except in so far as it directly affects the more 
general phenomena under consideration, but, in view of the large 
number of nucleolus-like bodies which are found in the egg nuclei 
of gymnosperms, it seems best at this point to consider these 
structures briefly as they appear in J. communis depressa. 
In the microspore mother cell there is always present a con- 
spicuous nucleolus which takes the chromatin stains and seems to 
be more or less intimately associated with the reticulum. Düring 
the nuclear changes which precede the heterotypic division this 
body gradually loses its affinity for dyes and at diakinesis has 
literally faded from view, apparently without having undergone 
any change in shape. Coincident with the Separation of the 
daughter chromosomes toward their respective poles there appear 
in the region of the spindle minute droplets, the so-called extra- 
nuclear nucleoli, which react slightly to stains, but which usual ly 
15* 
