256 BOTANICAL GAZETTE [September 



microspore being chiefly those of G. africanum. The inflorescence is described 

 and also the details of spermatogenesis from the mother cell to the microspore, 

 the reduced number of chromosomes being 12. Great interest attaches to the 

 male gametophyte of Gnetum, but the present account does not clear it up. At 

 pollination, three free nuclei were observed in the pollen grain, which "are 

 probably to be identified as one prothallial, one vegetative (tube), and one 

 generative." Since Lotsy has figured three free nuclei in the pollen tube of 

 Gnetum Gneman, which were obviously a tube nucleus and two male cells, the 

 free "prothallial nucleus" in the pollen grain is open to doubt. One would 

 like to be sure whether Gnetum has eliminated prothallial tissue or not. The 

 author says that "the germination of the microspore and the structure of the 

 pollen grain point to a much closer degree of affinity with Welwitschia than 

 with Ephedra" a conclusion which all other structures confirm. 



Miss Gordon 8 has discovered ray tracheids, both marginal and inter- 

 spersed, in old stem wood of Sequoia sempervirens. Since the wood of this 

 form is primitive enough in features to suggest its comparison with root wood, 

 the presence of ray tracheids is especially interesting. 



Wieland 9 has published an interesting account of Williamsonia, a genus 

 which he has done so much to elucidate. A few years ago a problematical 

 genus, it has now emerged clearly as a prominent Mesozoic group. An account 

 is given of its discovery, its structure, and its phylogenetic connections. Its 

 great range in habit, its variations in the structure of the strobilus, its variable 

 foliage, all suggest wide relationships, and among these suggested relationships 

 Wieland sees emphasized his contention that the angiosperms have been 

 derived from the Bennettitales. 



The same author, 10 in continuing his studies on the trunks of Cycadeoidea, 

 has discovered that some of the supposed young strobili are mature ones of 

 reduced type. This incidentally disturbs some of the previous conclusions as to 

 relationships among the species of Cycadeoidea, and especially extends our 

 knowledge as to the range of variation in the structure of the strobilus. These 

 reduced or simplified forms of course are more suggestive of the structure of 

 the angiosperm flower. — J. M. C. 



Inheritance of doubleness in stocks. — Doubleness in stocks (Matthiola) 

 presents one of the most complicated cases of inheritance yet thoroughly 

 studied, but Miss Saunders 11 has developed a scheme which allows a consistent 



8 Gordon. Marjorie, Ray tracheids in Sequoia sempervirens. New Phytol- 

 11:1-7. Jigs. 7. 191 2. 



9 Wieland, G. R., On the Williamsonian tribe. Amer. Jour. Sri. 32:433-466. 

 Jigs. 18. 191 1. 



10 Wieland, G. R., A study of some American fossil cycads. Part VI. On the 

 smaller flower-buds of Cycadeoidea. Amer. Jour. Sci. 33:73-91- figs* K« x 9 12 - 



11 Saunders, Miss E. R., Further experiments on the inheritance of "doubleness 

 and other characters in stocks. Jour. Genetics 1:303-376. pis. 2. Jigs. 2. 1911. 



