Morphologie, Teratologie, Befruchtung, Cytologie. 3 



Lawson, A. A., The Gametophytes and Embryo o f 5a- 

 adopitys verticüata. (Ann. of Bot. XXIV. p. 403-421. ill. 1910.; 



The life history, from spore formation to embryo, is described 

 in great detail. The following are the specially interesting features: 



The Upper part of the nucellus becomes differentiated into a 

 loose tissue of large thinwalled cells for receiving the pollen. At 

 the end of the first season's growth the male gametophyte contains 

 the tubenucleus, stalknucleus, and bodycell. In the« following sum- 

 mer the bodycell descends towards the tip of the pollen tube, and 

 two male nuclei of unequal size are formed immediately over the 

 neckcells of an archegonium. The contents of the tip of the pollen- 

 tube are discharged into a Single archegonium. 



The sporophyte has 16 chromosomes and the gametophytes 8. 



After ihe reduction division of the megasporemothercellnucleus 

 no cellplate is formed. The result of the second division is thus an 

 axial row of megaspores consisting of 3 cells, the middle one of 

 which contains two free nuclei. The basalcell becomes the functional 

 megaspore, and is surrounded by an archesporial tapetum. The 

 archegonia arise at the apex of the prothallium. They are 4 or 6 in 

 number, and each is enveloped by a Single layer of jacketcells. 

 During the fertilization period the inner walls of these jacketcells 

 become curiously modified by heavy, reticulated, chitinouslike 

 thickenings. A ventral canalnucleus is formed. The eggnucleus is 

 many times the size of either of the male nuclei. 



Agnes Arber (Cambridge.) 



Leehmere, A. E., Two embryosac mothercells in the 

 ovule of Fritillaria. (New Phytologist. IX. p. 257—259. 1910.) 



Two embryosac mothercells lying side by side, but separated 

 by a distinct wall, were found in an ovule oi Fritillaria messanensis. 

 They appear to have originated from two distinct archesporial cells. 



Agnes Arber (Cambridge.) 



Ovepton, J. B., The Organisation and recons truc tion of 

 the nuclei in the root tips of PodophvUmn peltatum. (Rep. 

 brit. Ass. Adv. Sc. Winnipeg. Sect. K. p. 678-679. 1909.) 



Although so much attention has been devoted to the study of 

 nuclear divisions, the behaviour of the nucleus in rest has been 

 comparatively neglected. In view of this, the author set himself 

 to follow the charges which the telophase chromosomes of Podo- 

 phyllunt peltatum undergo during their passage into the resting 

 nucleus, and the reformation of the visible chromosomes prepara- 

 tory to division. He finds that the chromosomes become vacuolated 

 while passing from the equatorial plate to the poles. Each chromo- 

 some eventually forms a reticulum , and the reticulum of the resting 

 nucleus is thus composed of a number of elementary reticula. The 

 author did not find the lateral anastomoses of marginal portions 

 of adjacent chromosomes described by Gregoire, believes that the 

 individual chromosomes, though they are in contact, do not anasto- 

 mose with one another. He also holds the view that the chromoso- 

 mes not only persist as individuals, but are also composed of 

 autonomous granules. Agnes Arber (Cambridge.) 



