692 Sargant.—Recent Work on the Results 
Order. 
Species. 
Monocotyledones. 
Observer. 
Orchid aceae 
Arundina speciosa . 
Nawaschin. 
Phajus Blumei 
Nawaschin. 
Phajus sp. 
Nawaschin. 
Himantoglossum hircinum. 
Strasburger. 
Orchis latifolia. 
Strasburger. 
0 . maculata. 
Strasburger. 
0 . mascula var . Hortii . 
Dicotyledones. 
Strasburger. 
Ranunculaceae 
Caltha palustris. 
Thomas. 
Delphinium elatum. 
Nawaschin. 
Compositae 
Helianthus annuus. 
Nawaschin. 
Rudbeckia speciosa . 
Nawaschin. 
Monotropeae 
Monotropa Hypopitys . 
Strasburger. 
The total number of species in which double fertilization 
has been recorded is thus twenty. These twenty species 
represent twelve genera (if Himantoglossum be included with 
Orchis ), and five orders, three of which are Dicotyledonous. 
Before we can properly estimate the collective value of the 
evidence, the difficulties of this branch of research must be 
considered. Material can be collected only in the flowering 
season. Excluding the four species observed before 1899, and 
the four collected and observed by Strasburger in 1900, we 
have twelve species belonging to nine genera, and repre¬ 
senting four families—two of them Dicotyledonous—as the 
result of one season’s pickling by three observers. The material 
for such work must be chosen from plants which are known 
to seed freely. The flowers must commonly be collected at 
least twice a day for two or three successive days, in order 
to secure the right stage, and each picking must be kept 
separate from the others throughout all the processes of the 
elaborate fixing methods, which are necessary in order to 
secure adequate preservation -of the embryo-sac. When 
observation of material thus collected and preserved begins, 
