212 



MONOGKAPH OF THE LABOULBENIACEJS. 



greater portion of its length, is more or less abruptly narrowed just before passing 

 into the venter. The contents of the venter during its active period, as it increases in 

 volume, pushes through the narrow opening in the diaphragm into the cavity of the 

 neck, and the portions thus extruded, when they have reached a certain definite size, 

 become separated from the mass whence they were derived ; and, assuming the form 

 of short cylindrical rods, the antherozoids pass into the general cavity of the neck, 

 the diameter of which is but slightly larger than their own, and thence make their 

 final exit through the terminal pore. This process of abj unction, by which small but 

 uniform pieces become separated from the contents of the venter as it is pushed into 

 the neck, continues for a period which varies somewhat in different cases, but may 

 begin some time before the female organs are mature, and continue long after they 

 have been fertilized. Although one sees many cases in which the neck contains a 

 continuous series of antherozoids which are evidently pushing one another out through 

 the terminal opening, these bodies seem to be able to make their exit quite inde- 

 pendently of one another, although at the same time they also appear to lack any 

 indication of a power of independent motion, amoeboid or other. 



As has been already mentioned, the form of the simple antheridium is subject to 

 inconsiderable variations which depend in general on the relative development of the 

 neck or of the venter, the latter being sometimes short and stout and abruptly dis- 

 tinguished, while in other cases it may run gradually into the neck without any such 

 clearly marked differentiation. The neck, too, may be short and rather stout, or long 

 and slender, straight or curved, the extremes in these respects being illustrated by 

 such instances as the following : Laboulbenia decipiens (Plate XX, fig. 20), L. Elon- 

 gata (Plate II, fig. 15), Teratomyces (Plate X, figs. 6 and 11), Compsomyces (Plate 

 XI, fig. 14), or Sligmatomyces Baeri (Plate I, fig. 26). 



The disposition of the antheridia, and their relation to one another on the same 

 appendage or branch, is a matter of much importance in affording generic distinctions, 

 and even, in a few cases, is of service in defining species. On this basis all the gen- 

 era having simple antheridia, with the exception of Amorphomyces, which has in- 

 variably a single antheridium, might be separated into two categories : those in which 

 the antheridial cells are disposed in definite series on the appendage, and those in 

 which they are more or less indefinitely placed. 



In the first category are found forms in which the series is a single one, as in 

 Stigmatomyces (Plates I, figs. 8-12 ; VIII, fig. 3), the antheridial cells succeeding one 

 another in a single vertical row, while a somewhat more complicated condition exists 

 in Idiomyces, where three vertical rows are present (Plate IX, figs. 18-19). Again, 



