and its relation to that in the Animal Kingdom. 255 



[Supplementary note. — Just before the printing of this essay, 

 we received, through the kindness of the author, Pringsheim^s 

 second memoir on the fecundation and alternation of generations 

 in the Algse*. This contains a full confirmation of the conjec- 

 ture in the preceding paragraph. Pringsheim saw developed in 

 a portion of the species of CEdogonium and in Bulhochcete, in 

 the end-cells of a structure [male plant) produced from a micro- 

 gonidium (now called androspore, to distinguish it from all 

 other, probably very diverse swarming bodies hitherto con- 

 founded together under the name of microgonidia) — in each a 

 spermatozoid furnished with cilia, which, after it had been set 

 free, completed the act of fecundation exactly in the same way 

 as in Vaucheria. In a portion of the species of CEdogonium the 

 spermatozoids are developed singly in determinate, successive 

 cells of the (Edogonium-\\iVQ2idL, which consists of only one row 

 of cells. In this case, Pringsheim applies the name of antheri- 

 dium to the whole sum of the cells forming spermatozoids.) 



In Achlya prolifera the antheridia are perhaps represented by 

 the branchlets, first described by Alex. Braun (also in ColeochcEte 

 pulvinataf), which apply themselves upon the sporangium, and 

 penetrate into the orifices of this by means of lateral, papillary, 

 projecting processes. In Bulbochcete, as also in Coleochcete and 

 probably in CEdogonium, the subsequent development of the 

 resting-spore is essentially different from that of Vaucheria, It 

 does not directly produce the thallus of the plant, but zoospores 

 (almost like the other zoospores of the same plant), by the ger- 

 mination of which is first produced the structure resembling the 

 parent plant. 



A similar condition, formation of spores of a third kind, accord- 

 ing to Pringsheim, occurs sometimes in the resting-spore of 

 Achlya proliferaX, probably also in Spirogyra jugalis^ ; whether 



* Monatsbericht der Berlin. Acad. 1856. 



t Alex. Braun, I c. (Ray Transl. 298). 



X Pringsheim, Entwiekl. der Achlya prolifera. Nova Acta A.C.L.C. xxiii. 

 pt. 1. p. 427. pi. 47. fig. 17. Vide also Nageli in Zeitschr. f. \\iss. Bo- 

 tanik, von Schleiden and Nageli, 3 & 4 Heft, p. 30, note (1846). 



§ Flora, 1852, p. 479. (Ann. Nat. Hist. 2 ser. xi. p. 210 et seq.) The 

 active spores here described by Pringsheim in Spirogyra jugalis, formed 

 sometimes in conjugated cells, sometimes in unconjugated young filaments, 

 probably occasionally also in the conjugation-body itself — which Nageli 

 was also acquainted with, and, since they did not appear capable of ger- 

 mination, compared with the ' swarming-cellules' (spermatozoids) of Fucus 

 (Botan. Zeit. 1849, p. 578) — are identical with Itzigsohn's ' spermato- 

 s/)/i«na' (mother-cells of spermatozoa) of Spirogyra arcta,Kutz. ; the cilia 

 of these spores doubtless constitute the little heads or tails of the discharged 

 spiral animalcules which Itzigsohn described. {Vide the letter of this autlior 

 on this subject to Tulasne, Ann. des Sc. nat. 3 ser. xvii. p. 150 (1852), and 

 his figures in ' Hedwigia,' 1852, No. 2. pi. 1, and in Botan. Zeitung,' 1853, 



