﻿1903] CURRENT LITERATURE 67 



of the root in S. Kraiisiana, S. delicatissima, and S. Poulteri, it is cen- 

 troxylic. — E. C. Jeffrey. 



Treub*^ has concluded that Fictis hirta produces parthenogenetic 

 embryos, and that this may be true of all the species of Ficus. Although 

 pollen grains on the stigma were observed to put out tubes, no tubes could 

 be found penetrating toward the sac or within the sac ; and yet there was an 

 abundance of developing embryos, from the undivided ^^g to a many-celled 

 stage. Treub supports this argument for parthenogenesis by the feeble 

 development of endosperm, and the poorly organized ^gg apparatus, especi- 

 ally the synergids ; but neither point seems to be well taken. In fact, the 

 evidence of parthenogenesis in this case is the repeated failure to find any 

 trace of pollen tubes where they ought to be in case fertilization occurs 

 The suggestion is made that the stimulus to segmentation in this case is the 

 puncture of the pollinating Blastophaga. Since there are only three recorded 

 cases of parthenogenesis among angiosperms, there is no reason why the 

 author should mention Juel's Antennaria and ^lurbeck's Alchemilla and omit 

 Overton's Thalictrum. — J, M. C. 



Shoemaker =' has obtained some interesting results from a study of 



Hamatnelis virginiana. In each anther two sporangia appear instead of the 

 usual four, and dehiscence is by means of a door-like valve hinged on the 

 side towards the carpel. The pollen grains show great resistance to low 

 temperature; some were observed to send out tubes after a week of cold 

 weather during which the temperature was at times as low as —15°. Per- 

 haps the most interesting fact is the long period between pollination and 

 fertilization, putting Hamamelis in a category with the Amentiferae in this 

 regard. Pollination occurs from October to December ; and the tubes at 

 once enter the nucellus and grow rapidly until cold weather. Live tubes 

 were found in January and February safely embedded in the hairy part of 

 the carpel. In the spring growth is resumed and fertilization occurs about 

 the middle of May, five to seven months after pollination. The endosperm 

 nucleus begins to divide after fertilization, and walls begin to appear at about 

 the r2-nucleate stage, the walls appearing first at the bottom of the sac. — 

 J. M. C. 



Massart^o has issued reprints of three papers on irritability. The first 

 and longest deals with positions of equilibrium toward stimuli acting alone or 

 together. Massart assumes an actual or possible transmission of a stimulus 

 in many cases where it has yet to be demonstrated ; the same experiments as 



"^Treub, M., L'organe femelle at I'embryog^n^se dans le Fiats hirta\2\i\. 

 Ann. Jard. Bot. Buitcnzorg II. 3:124-157. ph. 16-25. 1902. 



"^ Shoemaker, D. X., Notes on the development of Hamamelis virginiana L. 

 Johns Hopkins Univ. Circ. 21 : 86-87. 1902. 



3^ Massart, L, Sur Firritabilite des plants sup^rieures. I, II, III. Acad. Belgium 

 Mem. Cour. et autres M^m. 62 : reprint, 60 pp. 1902. 



