226 



MONOGRAPH OF THE LABOULBEXIACE^E. 



majority of instances to surround the individuals while their hosts are hiding in moist 

 situations. The genera in which the antherozoids are exogenous in origin probably 

 form an exception to this rule, and the transfer may be effected as above described 

 (p. 210). At all events, the trichogyne in the genus Zodiomyces always grows down- 

 wards (Plate XXIII, fig. 16) as it develops and seems to seek the antherozoid which is 

 almost invariably found attached to its tip (figs. 17, 18), and it is only after contact 

 with the antherozoid that it turns upward as is shown in the two last-mentioned 

 figures. In this instance several specimens have been examined in which there seemed 

 to have been a definite conjugation between the two organs, as in fig. 17 ; but as a 

 rule this union cannot be satisfactorily demonstrated owing to the very small size of 

 the male element. 



The fertilized trichogyne usually disappears before any definite change takes place 

 in the other cells of the procarpe ; but soon after this disappearance the divisions of 

 the carpogenic cell already described succeed one another with considerable rapidity, 

 and correspond at first in all the genera so far as they are known. The carpogenic 

 cell divides by two transverse septa into three superposed cells, the superior and infe- 

 rior supporting cells and the ascogonium; and the latter, at least in many of the instances 

 observed, becomes separated into a lower sterile part which has been above described 

 as the secondary inferior supporting cell ; while the upper part either remains without 

 further division, constituting the single ascogenic cell, as in Amorphomyces, Sphalero- 

 myces, Peyritschiella (Plate I, figs. 28, 29) and a few other genera ; or becomes divided 

 into two such cells, as in Laboulbenia (Plate I, fig. 35, ac) and in many other genera 

 in which this is the usual number. Less frequently the number of ascogenic cells may 

 be four, as in the case of Stigmatomyces above described ; while in only one genus, 

 Haplomyces, have eight such cells been definitely observed. Although the number of 

 ascogenic cells is moderately constant in a given genus, it does not appear to be inva- 

 riable, and I have seen rare instances in which two were present in forms having typi- 

 cally only one ; while in a single instance a specimen of Rhadinomyces was observed 

 in which three were distinct within the perithecium in place of the usual four ; a con- 

 dition doubtless due to the abortion of one of the original products of the division of 

 the ascogonium. 



The form of the ascogenic cell, though generally similar in most of the genera, is 

 subject to certain variations, and the position which it occupies in the cavity of the 

 perithecium is sometimes characteristic in given instances. In Rhizom3 r ces, for exam- 

 ple, it lies somewhat obliquely in relation to the axis of the perithecium, so that the 

 ascus mass has the appearance represented in Plate III, fig. 3 ; while in Chitonomyces 



