1916] FORSAITH—ONAGRACEAE 467 
In 1832 Dutrocuet (10) noticed the abortion of pollen 
grains in hybrids of Prunus. This relation, without doubt, 
received even greater rcognition under DARWIN’s influence in 18 59- 
The appearance of his Origin of species (5), in which he mentions 
the sterility of the offspring from hybrid parents, did much toward 
establishing this fact. The impaired fertility of garden varieties 
of plants likewise is valuable proof of this principle. The long- 
continued improvement of horticultural species by crossing has 
led to much investigation in this connection, and as a result many 
cases are on record where forms thus produced have become nearly 
or quite completely sterile. As an example of this form of sterility, 
conditions found in a garden hybrid of Fuchsia may be mentioned. 
This genus is well known to cross readily, and the resultant impo- 
_ tency of the sexual elements was observed by SmitTH (22) in 1876. 
In his article he states that the pollen in garden fuchsias “‘is always 
variable.” In a hybrid from Fuchsia splendensX procumbens he 
noticed that only about one-third of the pollen cells were triangu- 
lar in form, and the remaining two-thirds were of a “peculiar 
shape”’ which (in view of our later studies) may be interpreted as 
an indication of a tendency to abortion in the anther. During the 
Same year ANDERSON (1) states that only a few seeds in this species 
were potent, and a condition similar to this was cited by MEEHAN 
(21) in relation to cultivated varieties of Viola in 1880. 
Since this article deals more especially with pollen conditions 
in the genus Epilobium, reference is made to HAUSSKNECHT’S (17) 
monograph of the genus, in which he mentions several hybrid forms. 
In his discussion of these crosses, he speaks of pollen sterility in 
relation to hybridization as follows: ‘Das beste Merkmal gewahren 
dann in diesem Falle die Pollenkérner, welche ich bei primaren 
Bastarden in der kleinen und geschlossen bleibenden Anthere stets 
vollig verschrumpft vorfand. ... . ”” Statements similar to this 
were made by GuIGNARD (16) two years later in regard to hybrid- 
ization in Cistus, Begonia, Mespilus, and Crataegus, the pollen of 
which he describes thus: “Les grains de pollen fertiles représentent 
environs le quart du nombre total, le rest est formé de grains de 
dimensions moindres, presque vides de protoplasma, ou n’ayant 
qu’un noyau au moment de la maturité de l’anthére.” In his later 
