HISTORICAL SKETCH 9 



had anything but truth to recommend them; and how an academy 

 by rewarding such work gave fresh proof of the well-known experi- 

 ence that prize-essays are little adapted to contribute to the solution 

 of a doubtful question in science." 



Discovery of Sexual Fusion in Lower Plants. During this interval 

 greater progress was being made with lower plants and animals. 

 Thuret, in 1854, showed that in Fucus the eggs must be activated by 

 sperms before they can germinate to give rise to new plants, and 



A B C D E 



Fig. 6. The so-called development of embryo from pollen tube in Martynia lutea 

 (tp = pollen tube; em = embryo ;edp = endosperm; is = integument; se = embryo 

 sac). A, l.s. ovule. B-D, stages in development of "pollen-tube embryo." 

 E, older embryo, together with a few of the surrounding endosperm cells. (After 

 Schacht, 1850.) 



later he also obtained hybrids by associating the ova and sperms of 

 different forms. In 1855 Pringsheim observed spermatozoids in 

 the little horns (antheridia) of Vaucheria and showed that no further 

 development occurs unless the spermatozoids enter the ovum. The 

 decisive observation was made in 1856 in Oedogonium, where he saw 

 the moving spermatozoid come in contact with the egg and force 

 its way inside the latter. On the basis of these and similar dis- 

 coveries in lower animals, the German zoologist Oscar Hertwig 

 (1875) made a general statement that the essential feature of fertili- 

 zation is the union of two nuclei, one furnished by the male parent 

 and the other by the female. 



In the phanerogams, where sex was supposed to be more apparent 



