258 HOFMEISTER, ON 



direction and the first root downwards, the latter being 

 surrounded at its base by the ruptured membrane of the 

 cellular protuberance, as by a sheath. Upon the plate ex- 

 planatory of this process (1. c, t. 41, fig. 2385) an empty 

 anther idium is shown upon the prothallium, without how- 

 ever any mention of this organ being made in the text. 

 Two years afterwards Nageli published the discovery of the 

 antheridia and spermatozoa of the ferns ( c Zeitschr. f. 

 wissensch. Bot.,' Zurich, 1844, p. 168). He describes 

 the origin of the anthericlium, of the mother-cells of the 

 spermatozoa, and of the spermatozoa themselves, essentially 

 in conformity with the account given in the preceding 

 pages; he brings clearly forward the similarity of the an- 

 theridia of the ferns with those of the Muscinese and asserts 

 that the antheridia are very probably the male organs, 

 although it remained almost inexplicable to him in what 

 relation they could stand to the impregnation, which he 

 considered only to affect the spores. It is beyond ques- 

 tion that Nageli also observed the archegonia of ferns, but 

 misunderstood them : they are the organs which he describes 

 and figures (1. c, p. 171, t. iv, fig. 11 — 15) as many-jointed 

 antheridia. The real nature of the archegonia was first 

 correctly ascertained by Count Leszyc-Summski (' Zur Ent- 

 wickelungs-geschichte der Earrn-krauter,' Berlin, 1848). 

 He pointed out (1. c, p. 13) that the rudiments of the frond- 

 bearing plant always appeared on the underside of one of 

 the archegonia, inside a cavity sunk in the tissue of the 

 cushion of the prothallium, and he assumed that in order 

 to excite the development of this embryo, the entrance of 

 one or more of the spermatozoa was necessary. He ob- 

 served the cilia of the spermatozoa, but did not figure them 

 quite accurately. Suminski's correct conclusions were 

 arrived at by observations which were to a great extent 

 erroneous. He believed that the archegonium in its 

 youngest condition, and before its neck protruded above 

 the surface of the prothallium, was open at its apex ; and 

 that at this period the entrance of the spermatozoon into the 

 central cell took place, He called the latter the cavity of 

 the germinal vesicle and its nucleus the germinal vesicle 

 itself. He considered that the longitudinal development 



