70 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Embryogeny of the Sequoiacese.* — W. Arnoldi has studied the 

 development of the embryo in the family Sequoiacese, comprising the 

 genera Sequoia, Wellingionia, Taxodium, Cryptomeria, Cunningham! a, 

 Arthrotaxis, Glyptostrobus, and Sciadopitys, especially in Sequoia sem- 

 pervirens. 



From his observations the author concludes that the Sequoiacese do 

 not form a single sharply differentiated family, but that they are com- 

 posed of at least three distinct sections. The first two genera form a 

 distinct group, the Sequoiese ; Sciadopntys should probably be made the 

 type of a distinct family ; while Taxodium, Cryptomeria, and Cunning- 

 liamia might be referred to the Cnpre&sinese. 



The characteristics of the family Sequoiese indicate their antiquity. 

 In Sequoia (sempervirens) there may be one or more embryo-sacs, the 

 number being quite indefinite ; in Wel1i7igtonia (gigantea), more than 

 one never become fully developed. In these two species there are also 

 all possible transitional forms between a single sessile archegone and a 

 complex of archegones ; the solitary sessile archegones are never ferti- 

 lised, but represent functionless organs. The structure of the pollen- 

 tube, and to a large extent that of the archegone, in the Sequoiese, agrees 

 with that in Cupressinese, differing from the other families of Coniferse. 

 The Cupressinese have probably been derived from the Sequoieas, through 

 Taxodium and Cryptomeria. 



Development of the Oosphere and Fertilisation in Pinus Strobus.f 

 —An examination of the development of the " egg" (oosphere) and of 

 the process of fertilisation in several species of Pinus, especially 

 P. Strobus, leads Miss M. C. Ferguson to the following, among other, 

 conclusions. 



The time at which the archegones appear varies somewhat ; but in 

 general they can be detected about two weeks before fertilisation ; they 

 are usually found at the micropylar end of the prothallium. The 

 number of archegones varies in the different species from one to nine. 

 The number of cells of which the neck is composed varies between four 

 and eight. The ventral canal-cell is cut off about a week before ferti- 

 lisation. In the division of the central cell the spindle arises as a 

 multipolar diarch, and lies wholly within the nucleus. During the 

 maturation of the oosphere, many nutritive spheres arise in the cyto- 

 plasm. As the nucleus of the oosphere assumes its central position, it 

 increases much in size, and many threads arise in the cytoplasm sur- 

 rounding it. The cytoplasm of the oosphere presents a delicate net- 

 work. Immediately before fertilisation an opening appears in this 

 cytoplasm, apparently for the reception of the sperm-cell. At the time 

 of fertilisation an opening is formed in the apex of the pollen-tube, and 

 the cells of the male gametophyte which still persist, together with a 

 portion of the cytoplasm and some of the starch of the pollen-tube, 

 pass into the protoplasm of the oosphere. The larger sperm-nucleus 

 escapes from the protoplasm of the sperm-cell, and moves directly to- 

 wards the oosphere nucleus. At the time of conjugation the oosphere 

 nucleus is several times larger than the sperm-nucleus. There is no 



* Bull. Soc. Imp. Nat. Moscou, xiv. (1900) 1901, pp. 449-76 (2 pis. and 30 figs.). 

 Cf. this Journal, 1900, p. 482; nlso 189G, p. 047. 

 t Ann. Bot„ xv. (1901) pp. 435-79 (3 pis.). 



