744 JOHN BEARD, 



prolonged researches, "Versuche mit diöcischen Pflanzen in Rücksicht 

 auf Geschlechts vertheilung". The part of his memoir concerning us 

 here is that contained in: Biol. Ctrbl., V. 20, 15. Dec. 1900. It is a 

 matter of impossibility to give in a short space anything like an ad- 

 equate abstract of this elaborate memoir. It may be noted, that in 

 some points the author has reached conclusions similar to some of 

 mine. Thus (p. 766), it is recognised for plants, that during the 

 development nothing can influence the sex, and that this must be 

 already predetermined in the germ. On the other hand. Strasburger 

 (p. 771) accepts Dzierzon's theory of the determination of sex in 

 the bee by the omission or the occurrence of fertilisation. Indeed, 

 he goes further, and ascribes to all the eggs of the bee a strong 

 male tendency, which is supposed to be counteracted on fertilisation 

 by a still stronger female tendency on the part of the spermatozoon. 

 On p. 770, however, we read "when I relegate the separation of the 

 characters to within the pollen- and embryo-sac-mother-cells, it is quite 

 clear to me, that this conclusion means as much for every prothallus 

 of the Pteridophyta as the bringing-forth (Erzeugung) of sexual pro- 

 ducts of the like sexual tendency" ^). The characters here mentioned 

 are, however, not male and female ones. What they are is plain 

 enough from the context, and to this the reader may be referred. 

 The argument is based upon an analogy ; but, on p. 774 the author 

 writes: "the circumstance, that dioecious plants reproduce from the 

 embryonic substance of their growing-points [Vegetationspunkte] quite 

 generally only the one sex, is decisive for the view, that sex is already 

 determined in the embryonic substance." This idea, consequently 

 followed out, might possibly have led the learned author to conclusions 

 for plants, similar to those here adopted for animals. There may 

 well be difierences in detail. 



Just as there has long been an indication of the zoological way 

 in the two sorts of eggs — of different sizes and destinies — of 

 Hydatina senta, Phylloxera, and Dinophilus apatris (= gyrociliatus), 

 so unto the botanists there may have been given a sign in the micro- 

 spores and macrospores of Marsilia, Salvinia, and the majority of the 

 Lycopodinae. 



1) In the original written "Tendenz", not "Bestimmung". From 

 his explanation of the supposed course of events in the bee it is clear, 

 that Strasburger believes in the possibility of the alteration of the 

 "tendency" and the final determination of sex — its „Bestimmung" 

 — at fertilisation. 



