SPERMATOZOA AND PHYTOZOA. 149 



terminated by a long tail. Sometimes they are spiral in 

 their outline. We observe them more or less in the male 

 semen of all animals. 



The spermatozoa are the essential constituents of the 

 seminal fluid. The fluid without them has not in itself any 

 fertilizing power. Sometimes the seminal fluid is absent 

 altogether, so that they constitute the sole element of the 

 semen. The fecundation of the ovum is therefore accom- 

 plished, by contact with the spermatozoa which swim in the 

 seminal fluid. It seems to be by undulations of their tail 

 rather than by cilias that their movements are effected ; and 

 it is obvious that they are thus endowed with mobility, 

 in order to facilitate their access to the germinal vesicle of 

 the ovum. 



In all the orders of Cryptogamous plants, bodies analo- 

 gous to stamens and pistils, termed antheridia and pistil- 

 lidia, have been discovered. The mutual action of these 

 bodies is necessary to the development of all the orders of 

 the Cryptogamia. Now the cells of the antheridia of mosses 

 each contain a spiral filament which has a globular head and 

 a long tail, exactly like that of a spermatozoa, and when 

 examined with a power of 250 diameters, it is seen to be in 

 rapid motion in the cell. The spiral filament has therefore 

 been called a phytozoon, and is believed to exercise the 

 same function in the vegetable as the spermatozoon in the 

 animal economy. Similar phytozoa have been detected in 

 the antheridia on the pro-embryo of ferns, in that part of 

 the fructification of Chara, known as the globule; in short, 

 in all the organs, which represent the stamens, in Crypto- 

 gamous plants. 



The antheridia are globular in Chara, but they are some- 

 what ovoid in mosses. They are generally composed of a 

 mass of cells, variable in their form, each containing a 

 13* 



