AND GERMINATION OF ALGiE. 65 



of the spermatozoids into the female organ, with the utmost 

 distinctness and clearness, even into the minutest details of the 

 proceeding ; in a plant, in fact, so happily organized that the 

 fertilizing organs may be directly observed without injury 

 to it in its natural condition ; and in which, lastly, the 

 female organ, owing to its transparency, offers such a slight 

 obstacle to observation that the motion of the spermatozoids, 

 within it, may be closely watched for hours together, so long 

 as it lasts. I have noticed the gradual completion of both 

 sexual organs so far, as to be enabled to describe the con- 

 ditions presented in them, which immediately precede the 

 commencement of the act of impregnation. These circum- 

 stances place the phenomenon so much under the control of 

 the observer, that he is able j)reviously to determine the time 

 of the commencement of the phenomenon, and in a condition 

 readily to demonstrate the whole act of impregnation before 

 others. Lastly, since I have made these observations in 

 Vaucheria sessilis, one of the lowest of the fresh- water AlgoB, 

 it would appear that the process of impregnation is at 

 present more precisely known in one of the lowest divisions 

 of the vegetable kingdom, than it is in any of the other 

 higher plants, or in any animal ; nor does it, furthermore, 

 scarcely admit of doubt, that sex is a imiversal property of all 

 organisms, manifesting a wonderful analogy in the most highly 

 organized animals, as icell as in the simplest cellular jdants. 



1. The Vauclieria, besides the asexual multiplication by 

 zoospores, also exhibits a true sexual propagation, effected by 

 means of the two organs, known as the hornlets (Hornchen) 

 and spores. Even Vaucher, who first noticed these organs, 

 entertained a suspicion with respect to the nature of the 

 " hornlets," which he declared to be the anthers of the plant, 

 stating that the fertilizing pollen, which, as he thought, filled 

 the entire tube, was discharged through them. With his 

 means of observation he could scarcely have penetrated more 

 deeply into the nature of the process, and it is highly to his 

 credit that he should have advanced so far towards an expla- 

 nation of it. 



This view of Vaucher's with respect to the true nature of 

 the " hornlets," is far nearer the truth than are the assertions 

 of later algologists of the occurrence of a copulation of the 

 *' hornlet," and the contiguous spore, an assertion which is 

 at once contradicted by attentive consideration of the relative 

 positions of the mouth of the spore and of the " hornlet" 

 before and after impregnation. The notion arose fi'om a sup- 

 posed analogy between the phenomena of fructification in the 

 VauchericB and the formation of the spores in the SpirogyrcB, 



VOL. IV. F 



