1921] WALKER—GAMETOPHYTES OF EQUISETUM 389 
appear. Many gametophytes died, while others continued a slug- 
gish growth. They are still alive (March 1) and show some growth, 
although on the whole no increase in size is observable. 
By this same method spores of E. arvense, E. telmateia, and 
E. robustum sent from western Oregon, and of E. arvense from 
Chicago were also grown. ‘These spores were planted about a week 
after gathering, and all grew well. £. arvense and E. telmateia 
developed sporophytes freely, but E. robustum never developed 
sporophytes, although the thalli lived until September 1 and 
attained a diameter of nearly 1 cm. before they died. 
The fact that these spores grew well led the writer to plan some 
experiments in order to test the vitality of spores. Cones were 
taken when so green that the spores would not leave the sporangia. 
The cones were crushed and sprinkled on the soil. Others were 
planted when the spores were just ripe. Still others were kept in 
the laboratory in an open box for nine days. The cones were so 
dry they could be pulverized between the fingers when they were 
planted. In all cases equally abundant germination was observed, 
but the older the spores the longer the period before germinaton 
took place. Spores from green cones produced gametophytes of 
two and three cells during the first twenty-four hours, while 
gametophytes from spores dried for nine days required a week or 
more to reach the same stage. After being started they also 
developed more slowly.’ This agrees with BucuTIEN’s results. 
He found that after fifteen days germination decreased greatly, and 
after twenty-one days only about 1 per cent germinated, and the 
growth was much slower. Studies of these gametophytes and their 
development are in progress, and the results will be given in another 
paper. 
Summary 
The investigation of large numbers of gametophytes of E. 
laevigatum found growing in their native habitat yielded results 
which may be summarized as follows: 
1. The gametophytes are all of one kind. 
2. They consist of a flat circular disk 1-10 mm. in diameter 
bearing numerous upright green branches on their upper surface, 
