392 M. E. Claparede on the Theory of the 



acese, the Mosses aud the Characesej and we have strong pre- 

 sumptions that we are on the way to discover them in the 

 Floridese, the Fucoidese, the Lichenes and the Fungi. Lastly, 

 their existence has lately been ascertained by Pringsheim in the 

 freshwater Algse*. The analogy of these organs with the gene- 

 rative organs of animals is so great, that it is the sole reason for 

 their being regarded as organs of fructification ; for until within 

 the last few years we had no direct proofs of their function. 

 And yet botanists are now almost universally agreed to regard 

 them as organs serving for reproduction. It is an interesting 

 fact, that at the very moment when the discovery of the pene- 

 tration of the animal spermatozoid into the ovum startled the 

 zoologists^ that of the passage of the vegetable spermatozoid 

 into the archegonium appeared on the botanical horizon. It is 

 scarcely a year since Thuretf made known some remarkable 

 experiments made at Cherbourg upon the spores of Fucacese. 

 He found that the spores of these plants only germinate when 

 they are in contact with the mobile elements contained in the 

 antheridia, that is to say, with the spermatozoids (antherozoids). 

 When the spores are isolated, which is easily done in the dioecious 

 Fuci, they all perish without exception, and without any develop- 

 ment. This proves at least that the antheridia have a part to 

 play in the act of fecundation. But these experiments have not 

 the value of direct observations, and fortunately the want of 

 these is beginning to be supplied. Suminski has already 

 asserted, that he has seen the spermatozoa penetrate into the 

 archegonium of a Fern [Pteris serrulata). Hofmeister has ob- 

 served the same phaenomenon in another species [Aspidium 

 filix). These observations, however, have given rise to numerous 

 objections, reposing to a great extent upon the difficulties of 

 observation resulting from the tissue which envelopes the arche- 

 gonium. These objections can scarcely apply to Pringsheim^s 

 new discovery of the penetration of the spermatozoid into the 

 archegonium in VaucheriaX, where the sexual organs are so much 

 exposed, that we can scarcely suppose the possibility of error. 

 Besides the reproduction by zoospores, the Vaucherice present 

 another means of multiplication, which depends on the develop- 

 ment of their sexual organs ; namely, on the one hand of the 

 recurved horn-like organ, to which even Vaucher§ gave the 



* Ueber die Befruchtung der Algen. Monatsberichte der Berl. Akad., 

 March 1855. 



t Comptes Rendus, xxxvi. p. 745. 



X Ann. of Nat. Hist. 2nd Ser. xv. p. 347- 



§ Histoire des Conferves d'eau douce. Geneve, 1803. See especially 

 his Ectosperme sessile, pi. 2. fig. 7 "j^sessile seeds furnished with their 

 snther. 



