1916] FORSAITH—ONAGRACEAE 475 
County, Quebec. Here, it will be observed, nearly one-third of 
the microspores are destitute of protoplasm, and all the grains, 
with a single exception, are much reduced in size. In fig. 6 simi- 
lar indications of hybridism appear. In one case all the grains 
in a single tetrad, still remaining intact, have become defective. 
That like influences of degeneration may have caused many of the 
microspores of a Himalayan representative to stop growth in the 
early stages of development may be seen by reference to fig. 8. 
Several of the grains are perfectly developed, but a close observa- 
tion will show also many small sterile pollen cells among those 
which have reached maturity. 
A comparison of text fig. 1 and list I will show that there is 
a quite general tendency to abortion in that part of its range where 
E. angustifolium coincides with that of its nearest ally, E. lati- 
folium. Defective microspores as an indication of hybridization 
are indicated by an asterisk in the list. In text fig. 1 those regions 
where these two plants are coexistent are represented in solid 
black. In contrast to this, those where E. angustifolium occurs 
alone are represented by hatching. 
In view of the general principle of the correlation of pollen 
Sterility and hybridism, previously mentioned, these facts are sig- 
nificant. From these studies it is apparent that when EZ. angusti- 
folium grows within the range of its nearest ally, crosses take place 
which result in hybrid offspring. This relation is strikingly evi- 
dent from the morphological standpoint at least, when one takes 
into account the presence of defective microspores in specimens 
chosen from that part of its habitat coterminous with that of E. 
latifolium. In contrast to this condition there is the more constant 
development of the pollen in buds selected from the more southern 
Stations where FE. angustifolium is practically monotypic. 
LIST I 
STATIONS OF Epilobium angustifolium, SHOWING RELATION OF PERFECT AND 
DEFECTIVE POLLEN TO LOCALITIES; DEFECTIVE POLLEN INDICATED 
BY AN ASTERISK 
*Blanc Sablon River; Grand Falls, Newfoundland; East Avalon Penin- 
sula, Newfoundland; *North of St. Paul’s Bay, Cow Head, W. Newfoundland; 
*Curling, Bay of Islands, Newfoundland; *St. George’s Pond, near Bay of 
