Plants, and Parthenogenesis. 207 



laceration. All three varieties of the cells anastomose with one 

 another, whence it happens that the tubes seem to be the ends 

 of the cortical cells. 



If this mode of development of the apothecium be compared 

 with that of the sporangium of the foliaceous cellular Cryptoga- 

 mia, we find that the at first free central cell of the archegonium 

 of the latter, which becomes developed into the sporangium 

 (whilst its downward-growing lower extremity, the future seta, 

 coalesces with the receptaculum), presents an analogy with the 

 cell from which the hymenium is developed, inasmuch as the 

 peripheral ends of all its parts are united with the adjoining 

 tissue. 



The mother-cells of the spores are here retained after they are 

 completely transformed into sporothecse, whereas in the IVIosses 

 they become absorbed before the complete development of the 

 spores. Instead of the elaters of the Hepaticse, we here find 

 among the Lichens the paraphyses. 



By prolonged maceration in water the outer cortical layer 

 becomes dissolved, and the young apothecia are resolved into 

 endogenous cells, which are seen like rows of " daughtei-- cells " 

 on the free branches (figs. 2 « & 5 o). 



These cells recall in appearance those structures remarked by 

 Itzigsohn, and called spei-matia ; however, I have not been for- 

 tunate enough to witness the antherozoid movements in them 

 which Itzigsohn and Rabenhorst observed in the spermatia. 



The act of impregnation of Coenogonium recalls that of the 

 conjugation of the two diff'erent branches of Vaucheria (PI. IX. 

 fig. 23), from the intermingling of the chemically different con- 

 tents of which the formation of a germ proceeded. This cir- 

 cumstance, too, afl"ords still stronger evidence of a sexual act, 

 since, under altered vital conditions of the same plant, the same 

 organs carried out the second form of fertilization, which most 

 closely coincided with the normal proceeding (PL IX. figs. 24 a 

 and 26 «& A). 



The product of one act of fertilization is here, as among the 

 Mosses and Hepaticse and also some genera of Algae {Saprolegnia 

 aiadAchlya), not a single germ, but several or many; and between 

 the process of impregnation seen in the last-named Alga and 

 that in the Coenogonium the closest similarity obtains, inasmuch 

 as the archegonium does not receive the fructifying material on 

 one side only, but simultaneously in several parts, after the 

 fashion of the conjugation occurring among the Confervje. 



This history of the development of the apothecium of Coenogo- 

 nium points out the course we must pursue in order to convince 

 ourselves what is the function of Itzigsohn's spermatia, and 

 whether it be, as Rabenhorst and Tulasne imagine, sexual. It 



