Meyen's Report for 1839 on Physiological Botany. 171 



proceeds thus : When the seeds of Viscmn contain more than 

 one embryo, it is to be explained by the development or co- 

 hesion of two ovida, of which one is generally abortive, etc. 

 The green vascular covering which is seen on the ripe seed, 

 constitutes, according to M. Decaisne, a part of the fruit, and 

 is the endocarp. This will however be seen to be incorrect. 



^r. Schleiden* has published some remarks on the flowers 

 of the Loranthaceae, and particularly of Viscum album ; he 

 draws attention to the fact that this form of flower is proba- 

 bly the simplest which can exist, for it consists of two pairs 

 of leaves placed in a circle, which in the male flowers are 

 metamorphosed into anthers, and in the females have more 

 the nature of a calyx. Between these sits the straight, naked 

 nucleus, and the embryo-sac is said to be formed in the pith 

 of the stalk (peduaculus). The grains of pollen appear on 

 the top of the nucleus, enter into it several together, and 

 thus produce the Polyembryony. M. Schleiden considers 

 the berry to be the pedunculus, which has become succulent, 

 and whose tissue is metamorphosed into that harder and 

 firmer kind which forms the skins of the seeds. The regu- 

 lar form of the anthers of Viscum album is usually bilocular 

 and four-celled, but each cell is divided into several compart- 

 ments by partitions, and regular anthers seldom occur on 

 account of monstrosity. In Viscum verticillatum the spike 

 consists of three pairs of bracts; the upper pair has only one 

 flower, and each of the others three, which afterwards form 

 a " Verticillus spurius," while the end flower is wanting. In 

 Loranthus the point of the naked nucleus is lengthened so as 

 to assum.e the ajDpearance of a style. At the end M. Schleidan 

 observes, that the Loranthaccce, in a parasitic form, represent 

 the intervening step between the Coniferae and the higher 

 families. 



I have also published some observations on the formation 

 of the seeds of Viscum albumf. The Polyembryony so often 

 observed in the seeds of this plant is caused by the appear- 

 ance of several embryo-sacs together, only one of which, 

 however, usually becomes fully developed, while the others 

 are abortive ; I could not observe anything confirmatory of 

 the statement of M. Decaisne, viz. that the embryo in this 

 plant consists of several single embryos grown together. It 

 is by no means seldom that several embryo-sacs contained 

 in the same nucleus are fertilized, but six or eight -weeks 

 afterwards only one of them comes to perfect development ; 



* Botanische Notizen, In Wicginanii's Archiv, etc. v. 1839, i. 211-214. 

 f Noch einige Worte, etc. etc., pp. 39-50. 



