THAXTER. — MONOGRAPH OF THE LABOULBENIACE^E. 



247 



in the form of the appendages and pcrithecia, the former being longer and more slender, w ith more num- 

 erous septa, and the latter laeking the suhterminal ejevation, a condition which may, however, he due 

 to immaturity. 



RICKIA Cavara. 



Receptacle consisting of a single basal cell surmounted by a cellular portion, the cells of which are 

 arranged in general in three vertical series: a posterior series each cell of which may cut off externally 

 one or two small cells bearing secondary sterile appendages or antheridia, and which is terminated by a 

 single primary appendage borne on a two-celled base: an anterior series similar to the posterior, but 

 terminating in a peritheeium, and a median series ending opposite the base of the primary appendage 

 and extending downward to the basal cells of the other two series. Antheridia irregularly disposed, the 

 numbers varying in different individuals, wholly free, subtended by a blackened septum, flask-shaped, 

 compound. Appendages as in Peyritschiella. Peritheeium normally solitary. 



This genus, which bears a superficial resemblance to Peyritschiella, is clearly distinguished by its 

 free compound antheridia which, in general form and appearance, so closely resemble simple antheridia 

 that they were so described by Cavara. Stained preparations, however, show clearly that the antheridium 

 consists of a basal cell, immediately above the blackened septum, and that from this basal cell a small 

 number of antheridia] cells arise, discharging together through the common neck. The antheridial cells 

 are very small, and I have been unable to make out their disposition more exactly than is shown in Plate 

 XXXIV, figs. 12 and 13. The structure and development of the receptacle is peculiar and in the material 

 examined, which was obtained partly through the courtesy of Prof. Cavara and partly from the specimens 

 distributed by Rehm, does not correspond to the figures which accompany the original description in 

 Malpighia. The basal cell constitutes a stalk-cell, which may rarely be once-septate, as in fig. 8; but is 

 usually single. Above this, in the youngest individuals (fig. 1), a subbasal cell is distinguished; above 

 this two small superposed cells (fig. 4w), one of which may be exceptionally absent, form the base of a 

 terminal simple primary appendage (fig. 4v), distinguished by the usual blackened septum. This ap- 

 pendage, with its two basal cells, develops no further, and is carried upward, without change of form or 

 structure, by the further growth of the receptacle, which results wholly from the activities of the sub- 

 basal cell and its products. In the next stage, the subbasal cell is divided by an oblique septum, con- 

 necting its two opposite angles. The two cells thus formed may be conveniently distinguished as anterior 

 (on the perithecial side) and posterior. In the third stage (fig. 2) the conditions are similar to those of 

 the second, except that the posterior cell (at the right of y) has become divided to an upper (o) and a lower 

 (z) cell by a transverse septum. The lower of these two cells (fig. 3 z), then begins to'grow outward dis- 

 tally, to form later the first secondary appendage, which may or may not be associated with a first an- 

 theridium as in fig. 11, at right. In the next stage (fig. 4), the upper (o) of the two cells which have 

 resulted from the division of the posterior cell, divides into two cells by a longitudinal septum and the 

 remainder of the receptacle results from the activity of these two cells together with that of the original 

 anterior cell (y) at the right in fig. 4, which has, as yet, only elongated. Of these three cells, the anterior 

 (y) produces the anterior, or perithecial series of the receptacle, with its secondary appendages and an- 

 theridia; the posterior (x) produces the posterior series with its antheridia and secondary appendages; 

 while the middle cell produces the middle or axial series. The further development of these series will 

 be made sufficiently clear by an examination of the successive figures, if it is remembered that figs. 1, 3, 

 4, 7 and 10 arc drawn with the anterior side at the right; while in the remaining figures it lies at the 

 left. The activity of the three cells just referred to, (x) and (y), with the cell lying between them in fig. 4, 

 results from the separation of a terminal cell from each, which, acting as a scheitel-cell, continues to cut 

 off cells below, which, in the anterior and posterior series, become secondarily divided to produce the 

 small cells on which the antheridia and secondary appendages are inserted. While the anterior and 

 posterior series are morphologically branches, and their growth a terminal growth, the central axis is 



