i9o8] CURRENT LITERATURE 353 



fresh-water ponds by the drainage from the adjacent areas. The ponds subse- 

 quently became sphagnum bogs, with the usual succession of vegetation cuhninaling 

 in a white pine swampT The weight of this forest submerged it in the quaking 

 bog upon which it rested, killing the trees, and establishing more hydrophytic 

 conditions. The white pines then reestablished themselves and dominated the area 

 for a century, when the forest development was abruptly terminated by the influx 

 of salt water caused by the subsidence of the region and the consequent break- 

 ing-through of the barrier reef. The duration of the marsh from the establish- 

 ment of bog plants on the sphagnum to the present time is estimated at 420 years. 



— Geo. D. Fuller. 



■ 

 I 



■ Studies in the rusts.— Oli\^ has published abstracts'" of two recent studies 

 among the rusts. One deals with the conflicting statements of Blackm.\n and 

 Christman in reference to the sexual performance in the caeoma type of rusts. 



Olfve 



MAN 



pore; but he also finds that the process may begin through a xtry small pore, so 

 that the nucleus of the migrating protoplast may become stretched out or con- 

 stricted, thus giving the appearance of Blackman's "nuclear migration." OuvT 

 also finds that the two cametes difTer somewhat in time of development, and 



portant 



The other study is concerned with the origin and relationships of the more 

 compact, "cluster-cup" type of structure. It seems that large, irregular, muUi- 

 nucleate cells arise after the sexual fusion, and that the basal cells of the aecidio- 

 spore rows arise as the ultimate branches of these cells. Hence the cup structure 

 is derived from a limited and deep-seated group of cells, and the peridium arises in 



consequence. Olive 



former 



type is the last member of the evolutionary series in this group.— J. M. C. 



Endosperm of caprifigs.— Leclerc du Sablox^^ has discovered that in those 

 pistillate flowers of the caprifig in which Blastophaga has deposited eggs the endo- 

 sperm develops, although fertilization has not occurred. Such endosperm he 

 speaks of as parthenogenetic, and observes that it is digested by the larva m the 



both 



„_„^.... cases being complete. The parthenogenetic endo- 

 sperm differs strikingly from the ordinary kind, in the absence of cellulose walls, 

 dense cytoplasm, and ver>' large, often irregular nuclei, which are variable in 

 number. In the rare cases in which fertilization has occurred in a pisUUate flower 

 of the caprifig, endosperm identical with that of the "Sm)-ma fig" is formed, that 



^^^O^. E. W., The relation of "conjugation" and "nuclear migration" in the 



^sts. Science N.S. 27:213. 1908.. 



, The relationships of the aecidium-cup type oj 



- " Sablon, Leclerc 0U, Structure et developpement de Falbumenducaprifiguie: 

 Rev. Gen. Botanique 20:14-24. pi 6. 1908. 



rust. Idem 214- 



