Cytologie und Befruchtung. 19 



Petrunkevitch, A., Natural and Artificial Partheno- 

 genesis. (Am. Nat. Vol. XXXIX. p. 65—76. Feb. 1905.) 



Has to do with this phenomenon as seen in certain animal 

 iorms, especially as concerns the behavior of the Chromosom es 

 and centrosomes. H. M. Richards (New York). 



5tapf, 0., On the fruit of Melocanna bambusoides, Trin., 

 an endospermless, viviparous genus o\ Bambiiseae. 

 (Transactions of the Linnean Society of London. V'^ol. 

 VI. Pt. 9. 2^ ser. June 1904. p. 401—425. Plates 45—47.) 



The pericarp of Melocanna attains relatively enormous 

 proportions as compared with that of other grasses; it remains 

 fleshy, although rather hard and tough, and it has a very im- 

 portant share in the metabolism of the maturing and germina- 

 ting fruit. A vvell-developed System of vascular Strands, spread 

 through the pericarp in concentric arrangement, serves to convey 

 and clistribute the materials vvhich go to build up, feed and fill 

 the growing fruit. A portion of the reserves is deposited as 

 cellulose, and this adds to the strength of the pericarp, which 

 is also protected by a well-differentiated epidermis and by the 

 subjacent layers being collenchymatously developed; but there 

 is üttle in the pericarp to protect it and the inclosed seed for 

 any length of time from external influences. The seed is naked, 

 since there is no integument from the very first and the free 

 ovule-wall corresponds to a very small fraction only of the full- 

 grown embryo-sac and is lost completely in the pericarp. 

 Endosperm-formation does not go much beyond the initial 

 stages; the endosperm is soon exhausted, collapses, and is 

 finally crushed into an apparently structureless film , wedged 

 in between pericarp and scutellum, whilst the storage of nutrient 

 matter is shifted on partly to the pericarp and partly to the 

 scutellum. The author compares the collapsed endosperm 

 with the obliterated tissues, occurring in certain grasses be- 

 tween the starch-containing endosperm and the scutellum 

 (= Quellschicht, of Tschirch) and proposes the term dia- 

 phragm for such tissues, which seem to be a rather common 

 occurrence in other seeds also. The scutellum has increased 

 in bulk and sucking surface and is well equipped with mestome 

 Strands; the carbohydrates probably pass over into it as glucose, 

 and the author brings forth good evidence to show that the 

 Proteids are transfered as asparagine. The embryo is curved 

 in such a way that plumule and radicle lie immediately side by side; 

 the coleoptile and the following leaves are very similar to one 

 another. The fruit is viviparous; the seedling however attains 

 a considerable size before it forms perfect leaves ready to assi- 

 milate and hence the abundant supply of reserve-food, leading 

 io the large fruit. F. E. Fritsch. 



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