116 SUMMARY OF CURRENT RESEARCHES RELATING TO 



common occurrence of a change in the colour of the corolla. In Amelia 

 ecMoides he finds that the long-styled form exhibits only a slight decrease 

 of fertility when impregnated with its own pollen. 



Fertilization of Yucca. * — Mr. W. Trelease corrects Prof. Eiley's 

 observation with regard to the presence of a nectary in the stigma of the 

 capsular Yuccas, no secretion taking place from the stigma except that of 

 the stigmatic fluid. He confirms Eiley's statement tliat the yucca-moth 

 (Tegefiada yiiccasellci) deliberately goes to the stamen and accumulates a 

 supply of pollen on its remarkable spinose tentacles before beginning the 

 work of j)olliuation and oviposition. 



New Case of Parthenogenesis. f — Dr. A. Ernst describes a plant foimd 

 by him in Caracas, and named Disci phania Ernstii, belonging to the Meni- 

 spermacefe, which appears to exhibit true parthenogenesis. Female plants 

 which bore no male flowers, and which were grown perfectly isolated where 

 there was no possibility of the access of pollen from another i:»lant, produced 

 in three successive years an increasing number of fertile fruits. Dr. Ernst 

 was unable to determine whether the embryo was developed as an out- 

 growth from a cell of the nucellus, as in Coelehogyne, or whether it was the 

 development of an unfertilized oosphere ; but he believed it to be the latter. 

 The fertile flowers appeared to be developed on embryos with a thicker 

 rachis than the barren ones. 



(2) Germination. 



Formation of Endosperni-Tissue.| — According to observations made on 

 a number of species of dicotyledonous ])lants by Herr F. Hegelraaier, the 

 usual statement that the formation of the endosperm takes place in two 

 difiereut ways, either by free-cell-formation or by the division of the 

 embryo-sac, must be accepted with some modification. The cases included 

 under the former head are not referable to free-cell-formation in the strict 

 sense of the term, but rather essentially to the division of a protoplasm- 

 body. The term free-cell-formation can only be retained if it is applied 

 to all those cases where the formation of fresh septa appears to be quite 

 independent of the previous divisions of the nucleus. 



In Lonicera caprifolimn the protoplast of the broadly fusiform embryo- 

 sac, which is surrounded only by the thick integument, forms before 

 impregnation, as respects the greater part of it, a rather thin parietal 

 layer ; the nucleus being not in the centre, but in a peripheral position 

 close to the egg-apparatus. As the embryo-sac increases in size, the 

 nucleus divides by repeated bipartition. During the later stages of this 

 bipartition, a number of small vacuoles are formed in the parietal layer, 

 and the embryo-sac presents, on superficial view, the appearance of a net. 

 The entire embryo-sac may now become suddenly filled with a cellular 

 mass, and all intermediate stages occur between this and a simple parietal 

 layer. The division-walls of the tissue thus formed show the same capacity 

 for staining with carmine and iodine, and the same resistance to sulphuric 

 acid as the protoplasm. The cell-cavities of this structure are unques- 

 tionably derived from the vacuoles in the protoplasmic layer, the division- 

 walls from the separating bands of protoplasm. Differentiated septa of 

 cellulose are formed at a subsequent jieriod. 



In Viburnum and Samhucus the embryo-sac is shorter and broader than 

 in Lonicera. No vacuoles ai)pear in the jiarietal layer of i^rotoplasm ; the 



* Bull. Torrcy But. Club, xiii. (1886) pp. 135-41 (3 figs.). 



t Nature, xxxiv. (188G) pp. 549-52 (16 figs.). 



X Bot. Ztg., xliv. (1886) pp. 529-39, 545-55, 561-78, 585-96 (1 pi.)- 



