34 
FRED. ELFVING. 
not be distinguished with certainty during the process of 
tube formation. 
In most Dicotyledons no further divisions take place in 
the Pollen-body. In the following only two nuclei are 
found in the ripe Pollen-body, namely, Gilia tricolor^ 
Nicotiana tabacum, Salvia verticillata, Digitalis lanata^ 
Gloxinia lixjbrida, Torenia asiatica, Plantago media, Campa- 
mda rapuncidoides, Bryonia alba, Lysimachia punctata, 
Erica tetralix, Monotropa hypopitys, Peperomia claytonioides. 
Cannabis sativa, Rhus glabra, Rida angustifolia, Ricinus 
communis, Hippuris vulgaris. Ranunculus muricatus. Del- 
phinium decorum. Clematis viticella, Papaver dubium, Viola 
tricolor, Helianthemum polifolium, Ampelopsis hederacea, 
Oxalis lasyandra, Malva caroliniana. Polygonum rubrum, 
Begoniae sp., Sedum hybridum, Clarkia pulchella, Spirea 
villosa. Mimosa brachybotrya, Lathyrus silvestris. 
The development of all of these can be described in a very 
few words. The vegetative cell, which has become free, either 
remains spherical or becomes, as is more usual, spindle shaped. 
The parietal layer of cortical plasm sooner or later vanishes, j 
and the two nuclei become mutually freed. These nuclei are, | 
in their younger conditions, very easily distinguished. The 
nucleolus of that nucleus, w^hich originates from the large I 
cell, remains much longer thap the vegetative one. This ■ 
distinguishing sign vanishes, however; and in, or even earlier | 
than, the tube-formation period, by successive metamorphoses ' 
both in form and size, the two nuclei become so like, that it 
is impossible to distinguish them. Only in Cannabis sativa 
is the nucleolus of the nucleus of the large cell preserved 
in the tubes (10 per cent., twelve hours). In this case some- 
times one, sometimes another nucleus goes in front. In 
Monotropa the two nuclei preserve their nucleoli very long 
(5 — 30 per cent., twenty hours). An absolute distinction 
between them w’as nevertheless impossible. 
Almost all possible differences occur in respect to the form 
of the nuclei, from the round’ one of Rhus to the greatly 
elongated, almost thread-shaped nucleus of Sedum. Gene- 
rally they are almost elliptic in shape. 
Putting together the chief results of my examinations it 
would appear that in a particular stage of development before 
fertilization the Pollen-body of the Angiosperms is divided 
into two cells — a larger and a smaller, the ^G^egetative ” 
one — which latter, by further divisions, can form a two- to 
thrce-celled tissue (tliallus). 
This vegetative cell, or these vegetative cells are separated 
