132 University of California Publications. [zoology. 



the others are too indisitnct for measurement. As a whole they 

 are smaller than the upper blastomere, their nuclei measuring 

 about 5.4 p. The ova which fail of development and are free in 

 the various portions of the internode, vary in size from 10.8 /*• 

 to 7.2 /"-. Of these the smallest are invariably found at the 

 greatest distance from the tip. 



It is thus seen that ova increase in size from their origin at 

 the anterior edge of the tip to the proximal border of the ovary. 

 If, at this point, they unite with a bud, they may continue to 

 increase somewhat in size. If the bud develops into a polypide, 

 the ovum either becomes an aborted embryo or is absorbed with- 

 out further development. Those ova which form no union with a 

 bud are frequently found in the lower portion of an internode, 

 much diminished in size. Those which develop in ovicells will 

 be discussed later. 



The data afforded by the preceding observations show that 

 the time at which the genital products appear, both male and 

 female, is much earlier than that at which the buds arise. The 

 place of origin of each has also been shown to be different, and 

 that the close relation existing between bud and ovum at a 

 later period is secondary. Furthermore, it is shown that 

 any bud may form a union with an ovum, i.e., the possibility of 

 a union between genital product and bud is the same for both 

 males and females. As a matter of fact, however, every bud in 

 a female colony does not unite with an egg, nor conversely does 

 every egg succeed in uniting with a bud, a large number of ova 

 undergoing degeneration. Of those ova which effect a union 

 with a bud only a relatively small number give rise to lai'vas, 

 i.e., become inclosed in ovicells. It seems probable, then, that 

 certain buds only possess the possibility of developing into ovi- 

 cells, viz., those which arise at that point in the internode 

 where the ovicell is found. Any or every internode then has the 

 possibility of being a fertile one. The questions are, Why does 

 not every internode possess an ovicell ? And why do some 

 unions result in only a partial development of an embryo and 

 no ovicell ? What the determining factor is, is not known. A 

 struggle seems to ensue between the two elements, bud and 

 ovum, the oue obtaining ascendency over the other. The result 



