156 BOTANICAL GAZETTE (SEPTEMBER 
extrusion of the nuclei from the central region of the oogonium 
The process consists essentially in a centripetal movement ol 
the cytoplasm, and results in a massing of this cytoplasm inthe 
center of the oogonium in such a manner that the vacuoles and 
nuclei are carried to the periphery of the denser central portion 
thus developed. Behrens (’g90, 315) describes a somewhat similar 
condition in Vaucheria as follows: ‘‘ Der ganze Vorgang bestelt 
also in der Abldésung des gréssten Theils der Protoplasten von det 
Wand durch Vacuolisation der wandstandigen Plasmaschichtea.” 
This curious phenomenon was noted by Wager in A. candidit 
and subsequently by Berlese in A. Portulace. The process ® 
heretofore described is simple. In A. Bliti it is complex, bi : 
unique and full of interest; and as a complete knowledge * 
essential to an understanding of the further development of the | 
oosphere a detailed description must be given. 2 
The first hint of the centripetal aggregation is found al 
tendency of the cytoplasm to depart from the even distributio® 
shown by a young oogonium; and to collect in masses through 
out the interior (fig. 58). These denser portions run togethes 
forming fewer but larger masses (fig. 59). Thus several eee 
nent aggregations of cytoplasm may be formed, separated ins 
one another and from the wall by vacuoles of varying sizes VS 
60). These denser regions are homogeneous in structure, 
taining minute vacuoles of uniform size evenly distributed * 
matrix of cytoplasm free from granules. The dense egies 
tain no nuclei, because these are forced from the dense cyt 
to a position on its periphery. The dense centers — ove 
forcing out the vacuoles. This may result immediately 
condition shown in fig.67, but frequently the coalescence . : 
more slowly and irregularly, and often a reniform mass 1 ge 
the indentation on one side marking the juncture yet % ee 
The last gap narrows until only a few vacuoles pera ee 
its track (fig. 67), and these soon float outward sige is 
of cytoplasm, the rudimentary oosphere (jigs. 62, “ _ 
the vacuoles pass outward they often leave captive a ce 
wake (figs. 61, 62, 64), but these soon follow. A typ! 
