Cytologie und Befruchtung. — Descendenz und Hybriden. 307 



•qui regardent cette forme comme un hybride entre les deux 

 -especes. C. Queva (Dijon). 



Robertson, A., Spore Formation in Torreya callfornlca. 

 (New Phytoloj:^ist. Vol. III. No. 6 and 7. 1904. p. 133— 148. 

 With Plates III Und IV.) 



The externa! morphology of the male cones and ovules is 

 Jully described: the former pass the winter in the mother cell 

 vcondition and in them the synapsis stage of the reduction 

 division occurs about three months earlier than in the embryo- 

 sac mother cell. Starch appears in the mother cells when 

 the nucleus is preparing for the reduction division and does 

 not disappear until the pollen grains have become binucleate 

 -and are shed; no prothallia! cells are cut off. 



The ovules with nucellus and integument already diffe- 

 rentiated are found in the winter buds. The arillus begins to 

 appear by the end of April and at this time the integument 

 has overtopped the nucellus; the embryo-sac can be first 

 dlstinguished in the latter half of May. A well marked synapsis 

 stage precedes the reduction division and the lowest of the 

 four spores formed becomes the embryo-sac. Starch is present 

 when the mother cell first becomes distinguishable from its 

 neighbours, and it has not disappeared when the division into 

 iour is completed. The author discusses the significance of the 

 prothallial cells in the pollen grains of the higher Conifers and 

 suggests that the survival is correlated with the presence of 

 bladders in the exine. In Torreya no bladders are developed, 

 and it is suggested that in such cases the loss of the vestigiai 

 prothallus has been broug^ht about to secure lightness of flight. 



M. Wilson (Glasgow). 



Darbishire, A. D., Professor Lang'sBreeding Experi- 

 ments with Helix hortensis and H. nemoralls. (Journal 

 of Conchology. Vol. II. July 1905. p. 193—200.) 



The paper includes an abstract of Prof. Lang's experi- 

 ments: 



Two varieties of //. hortensis were shown to breed true 

 independently. On crossing them together they appeared to 

 exhibit ordinary Mendelian phenomena. A few individuals 

 obtained from a cross between H. nemoralls and //. hortensis 

 were intermediate in respect of size, resembled one or the 

 other parent in certain characters, and differed in shape 

 from both. 



The author criticises Prof. Lang's statement that his results 

 constitute „a brilliant confirmation of a part of Mendel'slaw", 

 and suggests the possibility of certain complications. 



R. H. Lock. 



20* 



