256 Dr. L. Radlkofer on Fecundation in the Vegetable Kingdom, 



the quaternary division of the spores of Mesocarpus, Staurocurpua, 

 and Tyndaridea, observed by Thwaites*, is referable here, must 

 be shown by further observation. Parallel to this stand the 

 conditions observed in the zoospores. Pringsheim has observed 

 their division in Achli/af ; and in QLdogonium vesicatum, Link, 

 the same observer saw the contents of a germinating zoospore 

 which had come to rest, transformed into a number of small, 

 active spores, which again germinated J. 



Similar sexual conditions are rendered probable in the Pal- 

 mellaceae, by the discovery of resting, red spores (together with 

 the zoospores). 



Cohn has not only likewise confirmed the observation of 

 Pringsheim on Vaucheria, but at the same time brought forward 

 a new example of sexual reproduction in the Algte, and in a plant 

 widely ditfeiing from Vaucheria, namely Sphaeropha annulina^. 

 The spermatozoids, externally resembling the microgonidia of 

 other Algsejj, which are developed in separate cells {antheridia) 

 and are discharged from these by a previously-formed orifice, 

 here fecundate still membraneless spores, formed by the divi- 

 sion of the cell-contents, in other cells (sporangia), to which 

 they make their way through minute orifices. Cohn does not 

 consider that observations justify his assuming a direct penetra- 

 tion of the spermatozoids into the primordial spore-cell; it 

 rather seemed to him as if they attached themselves on the out- 

 side of the spore, and were finally converted into mucilaginous 

 globules. The further development of the fecundated spore is 

 essentially the same as in Bulbochate. 



We have likewise recently received a satisfactory key to the 

 import of the conjugation of the Alga. Areschoug'sll observa- 

 tions on this in the Zygnemese lead him to the conclusion, that 

 the spores now and then observed in cells which have not con- 



p. 201. pi. 5.) Cohn regards the structures in question, not as reproductive 

 bodies, but foreign structiu-cs belonging to the domain of fermentation- 

 phienomena (Unters. iib. Mikroskop. Alg. u. Pilze. Nova Acta A. C. L. C. 

 xxiv. pt. 1. p. 160.) [This is decidedlv erroneous. — A. H.] 



* Vide Botan. Zeitung, 1846, p. 498. 



t Flora, 1852, p. 484, note. % Ibid. 1852, p. 482. 



§ Ferd. Cohn, Uel). Entwirkl. n. Fortpflanzuug der Spharoplea annulina. 

 Monatsb. Berl. Acad, ilav 1855. (Transl. in Ann. Nat. Hist. 2 ser. xviii. 

 p. 81.) 



Il Meyen (Pflanzenphys. iii. p. 446) asserts that he often observed in 

 very various Confervas, about the time when the spores are formed, an 

 innumerable quantity of small, spirally curled, and spirally or uudulatmgly 

 moving animalcules {spirilla), and he represents these m Spharoplea amiii- 

 lina, in plate 10. tig. 17 ; his drawing, however, agrees so little with Cohn's 

 description of the spermatozoids of these Algae, that it is difficult to sup*- 

 pose that Meyen really saw the same things. 



T Vide ' Flora,' 1855, p. 675 et seq. 



