268 Cytologie und Befruchtung. — Descendenz und Hybriden. 



Albiigo Ipomoeae-pandiiranae Svvingle is the most favorable 

 species of the genus for a study of Oogenesis and Fertilization. 

 Early stages in oogenesis are aboiit as in other species. In 

 zonation the protopiasm falls away from the wall of the oogo- 

 nium, so that the oosphere is suspended in the center. The 

 nuclei of the oogonium move outward into the periplasm so 

 that, when mitosis is completed, only one or two nuclei conti- 

 guous to the coenocentrum remain within the oosphere. 



The coenocentrum is larger than that of A. Blltl but not 

 so large as that of A. Candida. The zones of protopiasm 

 surrounding the coenocentrum are more highly developed than 

 in A. Bllti. The coenocentrum degenerates after the second 

 mitosis. 



The antheridial tube, which is shorter than in most species 

 of Albugo, discharges one nucleus into the ooplasm, and simul- 

 taneous with the discharge the oospore walls begin to form. 

 There is a slight thickening of the wall of the oogonium itself, 

 a feature not known to occur in any other species of Albugo, 

 but prominent in the spore of Sclerospora. 



Charles J. Chamberlain (Chicago). 



Jeffrey, Edward C, The Comparative Anatom y and 

 Phylogeny of the Coniferales. Part I. The Genus 

 Sequoia. (Memoirs of the Boston Society of Nat. History. 

 Vol. V. No. 10. Nov. 1903.) 



The author finds reasons, based mainly on the presence 

 or absence of resin ducts under certain definite conditions, for 

 considering that Sequoia has been derived from an Abietineous 

 stock. 



Resin ducts are shown to occur in Sequoia gigautea in the 

 first annual ring of vigorous branches of adult trees, in the first 

 year's wood of the peduncle, axis, and scales of the female 

 cone, in leaf traces of vigorous leaves of vigorous adults, and 

 in the neighborhood of a wound in the first spring wood formed 

 after the infliction of the injury, Traumatic resin ducts occur 

 similarly in all species of Abies, which may be taken as typical 

 of the Abietineae. 



In contrast to 6". gigantea there are no resin ducts in 

 6". sempervirens except as the result of injury. 



The occurence of resin canals in vS. gigantea is regarded 

 as an ancestral feature. The reasons given are the following: 

 1) They are found only in those parts and organs that are 

 most likely to retain primitive anatomical characters; 2) they 

 constantly appear in the wood formed around wounds. This is 

 likewise true of 6". sempervirens and of the Abietineae in con- 

 trast to the Cupressineae, etc; 3) there are resin ducts in the 

 fossil species of Sequoia. 



Assuming, therefore, a stock whose wood was characterized 

 by resin canals, Sequoia is referred to the parent stock of the 



