214 THE FORMATION 
7. Awned, acospores. These are almost exclusively grasses, in which the 
awns serve for distribution by wind, water, or animals, and even, according 
to Kerner, by hygroscopic creeping movements. The mobility in many cases 
is great. 
8. Spiny, centrospores. This group contains a few representatives which 
possess a moderate degree of mobility by attachment, as in Tribulus and 
Cenchrus. 
9. Hocked, oncospores. The members of this group are extremely numer- 
ous, and the degree of mobility as a rule is very high. All exhibit in com- 
mon the development of hooks or barbs, by which they are disseminated in 
consequence of attachment, though the number, size, and disposition of the 
hooks vary exceedingly. 
10. Viscid, gloeospores. In these, the inflorescence is more or less covered 
with a viscid substance, as in species of Silene, or the fruit is beset with 
glandular hairs, as in Cerastium, Salvia, etc. 
11. Fleshy, sarcospores. These are intended for dissemination by deglu- 
” tition, largely by birds; the effectiveness of the modification, depends in a 
large degree upon the resistance of the seed envelope to digestion. The 
mobility varies greatly, but the area over which migration may be effected is 
large. 
12. Nut-fruited, creatospores. This group includes those plants with nut 
fruits which are carried away and secreted by animals for food. 
13. Flagellate, mastigospores. These are plants with ciliate or flagellate 
propagative cells, i. e., zoogonidia, as in Protococcus, Ulothrix, Oedogonium, 
Ectocarpus, etc., or with plant bodies similarly motile, Bacteriaceae and 
V olvocaceae. 
265. Position of disseminule. The position on the plant of the organ to 
be disseminated, i. e., its exposure to the distributing agent, plays a consid- 
erable part in determining the degree of mobility. In the majority of plants, 
the position of the inflorescence itself results in maximum exposure, but in a 
large number of forms special modifications have been developed for placing 
the spores or seeds in a more favorable position. In both cases, there are 
often present also devices for bringing about the abscission of the seed or 
fruit. It is, moreover, self-evident that the height of the inflorescence above 
ground or above the surrounding vegetation is likewise of considerable im- 
portance in increasing the trajectory. It is yet too early to make a complete 
classification of contrivances for placing disseminules in the most favorable’ 
exposure, but the following will serve as a basis for future arrangements. 
1. In all operculate Discomycetes, and especially in the Ascobolaceae, 
where the asci project above the hymenium, the spores are raised above the 
