The motile spermatozoid of a fern {Dryopteris I'illarsii from Cyprus) killed with osmic vapour and 

 photographed with ultra-violet light at a magnification of three thousand diameters. The organs 

 of locomotion are numerous cilia, each of which is a tuft of still finer threads. The body of the 

 spermatozoid appears black because it is almost entirely composed of the nucleus which absorbs 

 ultra-violet light strongly. In life the body is tightly coiled. 



