668 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



cells. Of these the lower becomes the embryo-sac without further 

 division, whilst the upper cell degenerates. In B. Chafnpionii the 

 tetrad-divisions are more complete, and the mother-cell u^ii^iliy dlivides 

 into either three or four cells. The lowest of these cells becomes the 

 embryo-isac. The Burmanniaceae which have, up to the present, been 

 examined show a complete series of stages in the reduction of the 

 tetrad-division. In Gymnosiphon trinitatis there appears to be (accord- 

 ing to the researches of Johow) a perfectly normal heterotype and 

 homotype division, with a reduction in the number of chromosomes 

 and the production of four cells. In Thismia javanica four cells are 

 also produced, but there is no reduction in the number of chromosomes. 

 In Burmannia Championii four, three, and sometimes only two, cells 

 are produced from the embryo-sac mother-cells. In Burmannia Can- 

 dida the production of only two cells from the mother-cell is the rule, 

 while in B. coelestis the mother-cell undergoes no division at all, but 

 at once becomes the embryo-sac. The development of the embryo-sac 

 cell into the usual eight -nucleated embryo-sac, with egg-apparatus, 

 antipodal cells, and free polar nuclei, takes place in the usual manner 

 in both B. Candida and B. Championii. 



The question of the mode of fertilization of the Burmanniaceae has 

 been said to be uncertain by several recent writers {e.g. Engler). But 

 as long ago as 1840 Miers showed that certain Brazilian Burmanniaceae 

 are self-fertilized. This was confirmed by Warming in 1901, and now 

 once again the present authors find that both B. Candida and B. Cham- 

 pionii are self-fertilized. The pollen-grains usually germinate in the 

 anther of the stamen, and the pollen-tubes grow out along the con- 

 nectine to the stigma of the flower. 



After fertilization an interesting feature in the development of the 

 endosperm consists in the production of a " basal " or haustorial 

 cell, as the result of the first division of the secondary nucleus oi th& 

 embryo-sac. This early production of a " basal " cell, which under- 

 goes no further divisions, is characteristic of all the species of Bur- 

 mannia which have so far been examined. At a later stage the " basal " 

 cell develops a series of cellulose bars, which stretch across the cell 

 cavity. The very light and winged seeds of these two species of Bur- 

 mannia are most probably wind- dispersed. — R. B. 



Saw-flies and Wood- Wasps of the Family Tenthredinoidea, 



The. By S. A. Eohwer {U.S.A. Dep. Agr., Bur. Entom., Tech. ser. xx. 

 pt. ii. ; March 1911). — The paper deals with the saw-flies and horntails, 

 and comprises the families Tenthredinoidea and Siricoidea of Ashmead's 

 classification. — V. G. J. 



Saw-fly Genus Hoplocampa, Studies in the. .By S. A. 



Eohwer {U.S.A. Dep. Agr., Bur. Entom., Bull. Tech. ser. xx. pt. iv. : 

 May 1911; 4 plates, map). — This paper gives the result of studies of 

 the entire group representing species and genera which are of special 

 economic importance. — V. G. J. 



