111 
away from the conidiophore the stipe remains attached to the conidium, 
and as it can always be seen readily when the conidium is in suitable posi- 
tion, it serves as a ready means of recognizing the basal end of the conidium. 
The stipe is equally obvious and distinguishable in H. Nos. 3, 4, 5, 13-16, 
etc., though in H. No. 2 and certain other numbers the stipe is of somewhat 
different type. While in very rare instances catenulation of conidia was 
observed (Fig. 9, b), this is apparently much less frequent than in the forms 
Fic. 9.—H. No. 1: a, portion of a conidiophore bearing 
conidia; b, catenulate conidia—rarely occurring. 
described by Ravn. The apical end of the conidium is always obtuse, and is 
marked by a pale spot that was mentioned by Ravn (91) as occurring in 
H. teres, etc. Being of so distinctive a character, this end is always recog- 
nizable when the conidium is in a suitable position. We have, then, reliable 
means of identifying each end of the conidia: the basal stipe and the apical 
spot (Fig. 10). The latter, though not characteristic of all Helmintho- 
sporiums—for example, H. Nos. 2, 29, and others lack it—is characteristic 
of H. Nos. 1, 3, 13-16, and others. 
The color of the conidia of H. No. 1 ranges from pale-straw to light 
brown, and under some conditions shows a slight bluish-green tinge. While 
H. Nos. 2 and 28 were distinctly and constantly different from H. No. 1 in 
color, H. Nos. 1, 3, 13-16, etc., were indistinguishable on a color basis. 
The conidial outer wall—This wall (the episporium of de Bary, 9), 
which gives the color to the conidium, is extremely thin and very fragile 
