Orton: Parallelism Between Spore-Forms 
25 
Pleospora and Apiosporitim, the likeness between the conidia in 
one stage and the ascospores is very striking.® (Fig. 4.) 
A variation of the cases just mentioned, and one which might 
appear to be an exception, exists in several genera as V entiiria and 
Plozvrightia where the ascospores are two-celled and the conidial 
stages often unicellular but occasionally two-celled like the asco- 
spores. (Fig. 6.) It might be said here that the mere production 
of occasional two-celled conidia seems to be of sufficient impor- 
tance to prove the parallelism, but it is to be noted also that the 
one-celled spores germinate at both ends and thus function in the 
same way as does its two-celled companion. This makes the evi- 
dence doubly strong that the relationship between conidia and 
ascospores is very close. 
As I have already pointed out, it is manifestly impossible for 
more than one of the conidial forms of pleomorphic species to be 
structurally parallel with its ascospores. 
Accepting the pleomorphic character of a considerable number of 
Ascomycetes and allies, why is it not logical to suppose that this 
condition may be typical of the class and where it fails to appear 
it may be accounted for by the hypothesis that one or more stages 
have been lost during the evolution of the group? A majority of 
the apparent discrepancies in the parallelism of conidia and asco- 
spores may be explained on the supposition that the conidial stages 
corresponding to the ascospores of the species have been sup- 
pressed. This might well be true in such a family as the Hypo- 
creaceae where some of the most apparent incongruities appear. 
In this family, we find such species as Nectria galligena, N. disco- 
phora, and Hypomyces Ipomoeae, in which there is no such mani- 
fest similarity. On the other hand, however, in this same family, 
such species as Gibberella Sanbinetii, Ophionectria coccicola, and 
Calonectria graminicola present striking parallelisms. (Fig. 7.) 
8 Higgins, B. B. Contribution to the Life History and Physiology of Cylin- 
drosporium on Stone Fruits. Am. Jour. Bot. i : 145—173. 1914. Higgins pre- 
sented at the same meeting at which this paper was read a very interesting 
case of parallelism in the genus Coccomyces, which he has proved to be the 
ascigerous stage of Cylindrosporium. The genus appears to be pleomorphic, 
at least some species possess three spore stages besides the ascospores. Of the 
conidial stages, only the Cylindrosporium stage appears to function as infection 
spores and these are almost identical with the ascospores. (Fig. 5.) 
