XXXI 



It is well worthy of note that this subject was at the very same 

 time engaging the attention of von Mohl. The year in which Nageli 

 announced his discovery of the " Schleimschicht " was also the year 

 in which von Mohl described the "primordial utricle " (' Bot. Zeitg.,' 

 1844). Similarly, the year in which Nageli published his more com- 

 plete account of the physiological importance of the " Schleimschicht " 

 was the year in which von Mohl arrived at the comprehensive con- 

 ception of this living substance under the name of "protoplasm" 

 (' Bot. Zeitg.,' 1846. See also Nageli, " Primordialschlauch," in 

 ' Pflanzenphysiologische Untersnchungen,' 1855). 



But other treasures lie buried in the now almost forgotten pages of 

 the ' Zeitschrift fiir wissenschaf tliche Botanik.' Heft 1, which was 

 entirely written by Nageli, contains, besides the first part of the great 

 cell-paper, an interesting account of the remarkable Siphonaceous 

 .Alga, Caulerpa : a philosophical essay on the fundamental conceptions 

 of Botany ; and. finally, a paper with the title " Bewegliche Spiral- 

 faden (Saamenfaden ?) an Farren." This paper announces, in fact, 

 the discovery of the antheridia and spermatozoids of Ferns. Although, 

 from the facts of their development, their structure, and their 

 chemical reactions, Nageli rightly regarded the actively moving, 

 spirally coiled filaments as the equivalents of the spermatozoids of the 

 Mosses and other Cryptogams, still he expressed himself only tenta- 

 tively on this point, since he had failed to discover the female organ, 

 and had therefore been unable to observe the process of fertilisation. 

 Consequently this discovery remained incomplete until Leszczyc- 

 Suminski detected the female organs on the prothallia of Ferns 

 (1848), and Hofmeister established the homology of these female 

 organs with those of the Mosses, and called them by the same name, 

 "archegonia" (' Bot. Zeitg.,' 1849: 'Vergl. Unters.,' 1851). 



In Hefte 3 and 4 of the same periodical, Nageli published some 

 observations on the Rhizocarps ('Ueber die Fortpflanzung der Rhizo- 

 carpeen ;" also his criticism of Mettenius, on p. 293) which extended 

 to this group the discovery previously made in the Ferns. He points 

 out that the microspores (at that time known as " pollen-grains ") of 

 Pilularia, and by analogy those of its allies, do not, as asserted by 

 'Schleiden, grow out into pollen-tubes which effect fertilisation as in 

 Phanerogams, but that they give rise to free-swimming sperma- 

 tozoids. Here also he failed to discover the female organ, borne on 

 the prothallium (" Keimwulst"), developed by the macrospore (then 

 called the " embryo- sac ") ; and this is the more strange, because he 

 actually saw and figured the neck of the female organ sufficiently 

 clearly to be able to correct Schleiden as to the mode of fertilisation 

 in these plants, pointing out that what Schleiden had taken to be a 

 group of germinating pollen-grains were nothing more than the rows 



