1914] JEFFREY— SPORE CONDITIONS 331 



ous cases of hybridization, we may now advantageously turn our 

 attention to the consideration of the Onagraceae, the family which 

 has supplied the famous case of Oenothera Lamar ckiana. We may 

 conveniently begin with our common garden fuchsias, which are 

 known to be of hybrid derivation from Fuchsia magellanica, an 

 inhabitant of southern South America. Fig. 19 shows the inter- 

 esting pollen conditions found in certain cases in the cultivated 

 Fuchsia. Many of the grains are shriveled and empty. In other 

 instances still less pollen perfection was observed; in fact in some 

 flowers there is practically no functional pollen and the anther sacs 

 do not open, but dry up without dehiscence. In still other cases the 

 pollen does not definitely shrivel up, but the grains are of very 

 unequal size and contain a very scanty supply of protoplasm. 



Let us now turn to the genus Epilobium. Our common fire- 

 weed, which inhabits somewhat generally the Northern Hemi- 

 sphere, is illustrated in fig. 16. The figure includes all four anthers, 

 which are laid open in the plane of section. It will be observed 

 that the pollen in their cavities is perfect. The illustration is 

 purposely made to show a large amount of pollen to demonstrate 

 how normal the pollen development is in Epilobium angustifolium, 

 the common willow herb, or fireweed. Fig. 17 shows a similar 

 section of the flower of Epilobium hirsutum, the giant willow herb, 

 which occurs near ballast heaps and is not uncommonly cultivated 

 in New England. Even with the low magnification used . it becomes 

 at once clear that the pollen development is abnormal, some of the 

 grains being smaller and without protoplasmic contents. Fig. 18 

 shows a higher magnification of two of the anther cavities in this 

 species, and on the left may be seen two sound grains and five 

 abortive ones. On the right only abortive grains appear. The 

 pollen in certain species of Epilobium occurs in tetrads, and in a 

 smaller number of others it is quite separate at maturity. Those 

 with the latter condition of the microspores are quite commonly 

 put under the genus Chamaenerion. Epilobium hirsutum con- 

 sequently shows evidence of hybridism in the presence of abortive 

 spores in its anther cavities. For comparison with this type, the 

 pollen development of the genus Rhododendron in the Ericaceae was 

 examined. In a pure species, such as Rhododendron catawbiense, 



