250 SUMMARY OP CURRENT RESEARCHES RELATING TO 



Cross-fertilization in Hydrangea.* — Mr. T. Meehan shows, by some 

 studies in Hydrangea, that the variations in the species are of the most 

 contradictory character taken from the standpoint of benefits in the 

 struggle for life; while they are entirely consistent with the author's 

 view of variation for variety's sake. Hydrangea liortensis from Japan 

 has the ray-florets sterile, or rather it is the lateral florets of the com- 

 pound cyme that give the enlarged sepals and fail to perfect the gynoe- 

 ceum. The terminal florets are fertile. In H. qiiercifoUa all the lateral 

 florets are fertile, and it is only the terminal one that has petaloid sepals 

 and is barren. Will any one assert that these exactly opposite condi- 

 tions can have any bearing whatever as aids in a struggle for life ? It 

 is broadly asserted that we owe to the existence of insects the various 

 forms and colours of flowers. In the genus Hydrangea, however, we 

 have illustrations of the most dissimilar and contradictory variations. 

 The facts are absolutely inexplicable on any theory of the survival of 

 the fittest in the struggle for life ; but on the author's view of tiie 

 absolute necessity of variation for its own sake, the explanation seems to 

 him simple enough. 



Life-history of Yucea.f — Mr. T. Meehan continues his contribu- 

 tions to the life-histories of plants. This year (1888) Yucca filamentosa 

 commenced to bloom about the end of June. During the first week or 

 ten days of the flowering period, an enormous amount of moisture exudes 

 from every part of the flower. The moths become very active just after 

 sunset, travelling rapidly up and down over the moistened stigma, 

 apparently feeding on the moisture. When, however, half the blossoms 

 on the panicle have matured, the production of moisture ceases, and on 

 the evening of the 8th of July no trace of exudation of moisture could 

 be found, nor was there any during the whole remainder of the flowering 

 period. 



Flowering of Euryale ferox.| — Further examination of the mode 

 of flowering of this plant leads Prof. G. Arcangeli to the conclusion 

 that it possesses both chasmogamous and cleistogamous flowers, and that 

 the former exhibit all the peculiarities of flowers which depend on the 

 visits of insects for their fertilization ; their number is small compared 

 to that of the cleistogamous flowers. The author, however, agrees now 

 with Darwin's view that this plant is abundantly fertile when self- 

 pollinated. 



Germination of the Seeds of Euryale ferox.§ — Prof. G. Arcangeli 

 describes the structure of the seed of this water-lily, which is covered 

 by a large thick aril, the bubbles of air in the cells of which assist in 

 the floating and consequent dissemination of the seeds. The aril is 

 composed of two parts, an outer larger pulpy, and an inner smaller 

 corrugated cartilaginous portion. Within the aril the seed is inclosed 

 in a double integument. The nucleus is composed, as in Nymphsea, 

 Nuphar, and Victoria, of three portions — embryo, albumen (endosperm), 

 and perisperm. The endosperm consists of a single layer of cells, while 

 the perisperm, derived from the tissue of the nucellus, occupies the 



* Proc. Acad. Nat. Sci. Philadelphia, 1888, pp. 277-9. 



t T. c, pp. 274-7. Cf. this Journal, 1887, p. 116. 



: Atti Soc. Tosc. Sci. Nat., ix. (18S8) pp. 369-83. Cf. Ihis Journal, 1858, p. 88. 



§ Nuov. Giorn. Bot. Ital., xx. (1888) pp. 467-73. 



