156 



MORPHOLOGY OF ANGIOSPERMS 



nounced at a meeting of the Russian Society of Naturalists in 

 August that it occurs in Lilium Martagon and Fritillaria ten- 

 ella. In 1899 Guignard 32 observed the same phenomenon in 

 Lilium pyrenaicum, Fritillaria meleagris, and Endymion 

 nutans. During 1900 the literature of the subject increased 

 rapidly. Nawaschin 40 added Juglans, Delphinium elatum, 

 Rudbeckia speciosa, and Helianthus annuus to the list, and in 

 certain orchids (Arundina and Phajus) he found the second 

 male nucleus consorting with the polar nuclei, but there was no 

 fusion. Guignard 39 described the phenomenon in species of 

 Tulipa (Fig. 72), also 42 in Scilla, Narcissus, Reseda, and 

 Hibiscus ; and Strasburger 43 not only added Himantoglossum, 



A 



B 



FIG. 72. A, embryo-sac of Tulipa sylvestris, showing nuclei scattered irregularly, each 

 nucleus surrounded by a rather definitely limited portion of the cytoplasm ; x 300. 

 J?, T. Celsiana, showing double fertilization in sac like that shown in A ; the male 

 nuclei recognized by vermiform appearance ; x 333. After GUIGNAKD." 



certain species of Orchis, and Monolropa Ilypopitys, but dis- 

 cussed the whole subject. Miss Thomas 44 > 45 reported double 

 fertilization in Caltha palustris ; Guignard 42 announced it in 

 Ranunculus Flammula, Helleborus foetidus, Anem.one nemo- 

 rosa, Clematis, Viticella, and Nigella sativa, and independently 

 confirmed its occurrence in Caltha palustris. Land 38 found it 

 in species of Erigeron and Silphium ; it was observed repeatedly 



