282 TEANSACTIOXS AND PKOCEEDIXGS OF THE [Sess. Lix. 



chromatin and linin. Accepting the term "Id" proposed 

 by "Weismann, Strasburger applies it to these discoid 

 elements composed of chromatin and linin, and concludes 

 that reduction consists in "the fusion in pairs of the ids, 

 and therefore also of the chromosomes." If this be so, we 

 see in the process of reduction the last, and perhaps the 

 most important step in the process of sexual coalescence. 

 It may strike us with surprise that a considerable interval 

 should elapse between the first and last steps of the process. 

 Take the case of Coryplia unibracv.lifera, which may grow 

 for sixty or eighty years without flowering. During all this 

 period the initial, but, on the above view, not the final steps 

 of sexual coalescence would have been taken. The neutral 

 sporophyte would, throughout its vast body, developed 

 through long years, retain the individuality of the ids of 

 the two parents ; the final fusion only taking place in the 

 spore-mother-cells of the inflorescence. But while con- 

 templating with astonishment such extreme cases as those 

 of the late-flowering Angiosperms, where a very long interval 

 may thus elapse between the first and last steps of sexual 

 coalescence, it is to be borne in mind that comparison 

 teaches by how gradual steps that extreme condition was 

 attained. In view of the facts derived from the Alg?e and 

 lower Archegoniatfe, the acceptance of the above conclusion 

 becomes less difficult. 



The idea of such an interval is, moreover, not an entirely 

 new one, for Pringsheim, in 18V8, had written to the effect 

 that two phases are to be distinguished in sexual coalescence 

 of vegetable cells — conjugation and connubium. His 

 definition of these is as follows : " Copulation appears as 

 a fertilising relation of the mother-cells of the sexual 

 elements ; connubium as a similar relation of the ultimate 

 sexual elements." (Pringsh. Jahrb., Bd. xi. p. 18.) His 

 application of this definition is, it is true, widely difierent 

 from that which might now be based upon it ; but the 

 fundamental idea is the same, viz, the elapse of an interval 

 of time between the more apparent, and the ultimate and 

 more intimate steps of the process of sexual coalescence. 

 According to our present view that interval will amount to 

 the whole vegetative period of the sporophyte, from the 

 point of coalescence of the male and female cells to the 



