THE NUTRITION OF THE EGG IN ZAMIA. 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY. 
LVI. 
IsaBEL S. SMITH. 
(WITH SIX FIGURES) 
For some time previous to the cutting off of the ventral canal 
cell, the central cell in most gymnosperms is surrounded by large 
prominent cells called the ‘jacket cells,’ which contain particu- 
larly large nuclei. The inner walls of the jacket cells, in contact 
with the egg, are pierced by numerous pores (fig. 2). During 
the rapid growth of the central cell the jacket cells and their 
nuclei are prominent; but during the period of free nuclear divi- 
sion in the embryo the jacket becomes less conspicuous, and 
finally becomes indistinguishable as a definite nutritive layer. It 
is evident that the jacket cells contribute to the growth of the 
central cells, and afterward to the growth of the egg and pro- 
embryo. The passage of various contents of the jacket cells into 
the egg has been described by several observers. 
Goroschankin (4) says in regard to Ceratozamia : “In fresh 
preparations mounted in water, each canal is seen to be filled 
with fine protoplasm that passes over sometimes into the proto- — 
plasm of the neighboring cells and sometimes into the proto- 
plasm of the egg cell. Transverse and longitudinal sections of 
fruits which were carried up with strong alcohol showed me the 
following: under the action of the alcohol the protoplasm of the 
surrounding endosperm sheath seems wholly smooth or with 
scarce observable projections on the side nearest the egg. But 
as for the protoplasm of the egg, it appears covered with pro- 
jections the length of which equals nearly or wholly the length 
of the canals. Afterward I began to make tangential sections of 
the egg from alcoholic preparations. Now I was able to see the 
sieve plates in the canal. .... From my observations on the 
egg wall in the cycads, the following conclusions were reached: 
346 [war 
