1014 SUMMARY OF CURRENT RESEARCHES RELATING TO 



remains still attached tu the receptacle, and undergoes further 

 development. (2) Tho perianth simply withers and decays under 

 the influence- of the atmosphere (3) The separation is effected by 

 the growth of the ovary ; the base of the perianth usually remains in 

 this case as a membraneous fringe. When a perianth whorl persists 

 until the fruit is ripe, as is often the case with the calyx, it may 

 assume somo of tho functions of tho wall of the ovary. 



/8. Physiology.* 



Embryogeny of the Santalacese.f — M. L. Guignard describes in 

 detail the structure of the embryo-sac and embryo of Thesium. Tho 

 original nucleus of the embryo-sac divides into two, and each of these 

 again into two, hut not always simultaneously. The antipodals do 

 not developo into cells at the bottom of the sac ; their nuclei disappear 

 very early. M. Guignard was able to follow the coalescence of the 

 two polar nuclei, giving rise to the secondary mxeleus of the embryo- 

 sac. At the summit of the sac tho two synergidae with very small 

 nuclei are readily distinguished from the oosphere, which is inserted 

 laterally, and usually on the inner side nearest the placenta. The 

 oosphere has also a more obvious membrane and a larger nucleus. 



In Osyris the placenta produces, as in Thesium, three ovular 

 papillae. The embryo-sac originates from a sub-epidermal cell, which 

 divides into two. The lower of these divides into three, and it is the 

 lowermost of these cells which forms the embryo-sac. The embryo- 

 sac in each of the three nucelli is impregnated, but an embryo de- 

 velopes in only one of them. The embryo of Osyris, like that of 

 Thesium, is without suspensor, resembling that of some Leguniinosae. 

 Neither the ovule nor seed has any proper integument ; in the seed it 

 is replaced by the wall of the ovary. 



In Santalum M. Guignard confirms the more recent statement of 

 Strasburger J that there is, as in other plants, only a single oosphere, 

 which descends, as usual, lower than the synergidae. One of these, 

 inclosed in a cellulose membrane, persists by the side of the oosphere, 

 and was at one time mistaken by Strasburger for a second oosphere. 



The structure of the reproductive apparatus of Santalaceae is, 

 therefore, of a higher grade than that of Loranthaceae, and approaches 

 more nearly the ordinary structure of Angiosperms. The antipodals 

 do not disappear so soon in Osyris as in Thesium. In Santalum, they 

 remain up to the moment of impregnation. After impregnation the 

 oosphere does not at once undergo division, but accumulates, in the 

 first place, a supply of starch. 



Position of the Nectaries in relation to Fertilization^ — Herr K. 

 F. Jordan describes the structure and position of the nectaries in a 



* This subdivision contains (1) Reproduction (including the formation of 

 the Embryo and accompanying processes) ; (2) Germination ; (3) Nutrition ; 

 (4) Growth; (5) Respiration; (6) Movement; and (7) Chemical processes (in- 

 cluding Fermentation). 



t Ann. Soi. Nat. (Bot.), ii. (1885) pp. 181-202 (3 pis.). 



t See this Journal, v. (1885) p. 830. 



§ Flora, lxix. (1886) pp. 195-210, 211-25, 243-52, 259-74 (2 pis.). 



