554 THE GAMETOPHYTE OF PSILOTUM 



glass was placed on the tup of the pot, the inequalities of the 

 lim providing sutlicient ventilation foi- the spores. The pot was 

 placed on the window-sill in my room, and exposed to bright 

 sunlight in the afternoon. Water was suppliefl by means of a 

 saucer and by an occasional bath up to the soil-level, water on 

 the top being, of course, avoided. It should be said that the 

 i-hizomes used were soaked in water for a day or two, to get rid 

 of spores, dirt, or insect-pests, which were removed with a soft 

 brush. Decayed scales were also removed, and only healthy 

 ones left. 



In this experiment, instead of waiting for the appearance of 

 jnuthalli, T made a thorough examination of some (jf the sjDores 

 as often as possible, both day and night. The examination was 

 continued until nearly all the spores were exhausted. 



On December 20th, atlditional spores, freshly gathered, were 

 sown on the same rhizomes, and these were continuously ex- 

 amined up to the end of the year, but without any definite 

 results. 



On New Year's Day, 1916, however, I was rewarded by seeing 

 the male gametophyte attached to the »pore. There were at least 

 foui', or more, antheridia visible, some of them already discharg- 

 ing antherozoids, and others almost ready to do so. 



This discovery cleared vip what had been, to me, a mystery foi 

 many weeks. I had frequently seen, and increasingly so towards 

 the ^\\(\ of Decembei-, bodies that now proved to have been the 

 antheridia of Fnilotnm discharging antherozoids. I had not 

 dreamt, at the time, that these bodies were the sperm-cells of a 

 vascular cryptogam; they seemed, to me, a phase of the life- 

 history of some organism ipiite unknown to me: a surmise all 

 the more probable seeing that every fresh collection of spores 

 placed under the microscope was associated with many forms of 

 life, including Tnfus(jria, Protozoa of various kinds, Tardigrades, 

 Mites, and Worms. 



The ditHculty experienced in recognising these antheridia will 

 be understood when it is stated that the first examples seen were 

 solitary spherical cells of various sizes, some of them equal in 



