70 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



the distribution of the wood parenchyma is consequently in radial bands, 

 which frequently become interrupted by the expansion of vessels and 

 fibres. The author has previously shown {Bot. Gaz., 1918, 65, 83-90), 

 that in regard to the similarity of the wood-vessels with those of angio- 

 sperms, we are dealing with a case of parallel evolution and not of 

 genetic relationship. If two such striking points of resemblance as 



Wood, cambium and young bast of Gnetum latifolium^ showing sieve- 

 tubes and companion-cells formed from different rows of cambium 

 cells ; also wood-parenchyma formed inwardly from those cambial 

 cells which form companion-cells. 



vessels in the wood and companion-cells in the bast are the result of in- 

 dependent evolution in Gnetum and angiosperms, the inference is natural 

 that other resemblances may be in the same category. x\. B. R. 



Hybrid Sarracenias and their Parents. — A. M. Russell {Univ. 

 Pennsy I. Philadelphia : Thesis^ 1919, 1-41, 5 pis.). The author has 

 studied several species of Sarracenia in order to compare their macro- 

 scopic structures with those of their parents. The hybrid forms are 

 intermediate in nearly every detail. Thus, the size of the hybrid is 

 intermediate, although there is frequently increased vigour, a feature 

 especially noted in hybrids of S. Moorei and S. areolata. The inter- 

 mediate shape is best seen in S. Catesbsei, while other hybrids exhibit a 

 distinct blending of botli parents, especially in smaller details, such as 

 the character of the lid. In colour intermediate blending is well 

 shown, but with half the intensity of the colour of the parents. The 

 flowers resemble those of both parents, but tend to be larger and more 

 showy. All the above characters are readily visible to the naked eye, 

 but the same intermediate features extend to the microscopic structures. 

 The epidermal cells of the pitcher and the lid resemble those of both 

 arents, and the number of stomata is an exact arithmetic mean of the 



