300 Trans. Acad. Sci. of St. Louis. 



of the spermatozoid into the archegonium of Pteris serrulata 

 and in Ceratopteris, He saw it disappear within the egg 

 itself and observed the formation of a membrane around the 

 fertilized egg within a very few minutes afterward. The 

 entire process required a very few minutes, but the actual 

 relations of the nuclei were scarcely touched. A fusion of 

 the two nuclei in the resting stage has been described by 

 Wager and Harper in fungi, by Oitmanns in Vaucheria, by 

 Farmer and Williams in Fucus. Campbell has described 

 changes in the spermatozoid of Pilularia before its fusion with 

 the Ggg nucleus which point to a similar occurrence in that 

 form. Ikeno has figured the entrance of the spermatozoid 

 nucleus unchanged into the Qgg nucleus in Cycas. Shaw has 

 made the same observation in Onoclea. 



The entrance of spermatozoids into the archegonium can be 

 easily observed under the microscope. I have not, however, 

 attempted to control it in many cases. By removing prothal- 

 lia from the soil and flooding considerable numbers in a dish 

 together, I believe that I get the nearest approach to normal 

 conditions. In this way I have secured a fairly representative 

 series of stages. 



After treating them as described above, the mouth of the 

 archegonium will generally be found to contain a number of 

 spermatozoids varying commonly from one or two to twenty 

 or more. When the number is large they are usually so 

 wound together that it would be hopeless to attempt to 

 trace out the relations of each (figs. 1 and 2). Shaw 

 has observed the spermatozoids *' swimming into the arche- 

 gonium, swarming over the egg and escaping again," yet 

 he notes that as they become entangled in the slime at 

 the mouth of the archegonium their progress is impeded 

 and the cytoplasmic vesicle torn off". I have found that 

 spermatozoids are attracted toward and enter archegonia 

 which have degenerated. They may be found piled upon 

 egg cells which have passed the stage of maturity and lost 

 the capacity for fertilization. In such cases the amount of 

 slime at the mouth of the archegonium would not prevent the 

 free entrance and exit of spermatozoids. From my own ob- 

 servations I doubt if a spermatozoid, after once entering the 



