182 



not by Mackel. Miss Walker also obtained male plants of this spe- 

 cies in culture. Careful examination of the prothallia of two other 

 species of this genus has been made by Rumberg (1931), who gives 

 an excellent review of the literature of the entire subject. Gameto- 

 phytes of E. dehile in India were investigated by Kashyap (1914, 

 1917), who states that a well-grown prothallium of this species may 

 be as much as three centimeters in diameter ; he figures one, natural 

 size, of nearly two and one half centimeters. Small prothallia of this 

 species, either male or female, were obtained under crowded con- 

 ditions in culture by Kashyap. 



Among the older accounts of the gametophytes of Equisetiim 

 may be mentioned the classical studies of Buchtien (1887), Sade- 

 beck (1881), and Jeffrey (1899). Excellent reviews of the litera- 

 ture are given by Sadebeck (1900), Goebel (1930), Campbell 

 (1930), Eames (1936), and Smith (1938). 



Although it is not difficult to grow spores of Equisetum in cul- 

 ture, they have not been found under natural conditions very often. 

 In spite of its wide distribution and common occurrence, this seems 

 to be especially true of E. arvense. Eames (1936), for instance, 

 states that gametophytes of this genus grow "on wet soil in shaded 

 places," but that they "are rarely found in the wild." Smith (1938) 

 states that they "are generally found growing on clayey soil and in 

 the mud belt along the banks of streams." 



At Orehill, Connecticut, a tiny hamlet between Lakeville, Con- 

 necticut, and Millerton, New York, there is a large open iron mine. 

 According to local accounts, this mine was worked from about the 

 year 1700 until shortly after the first World War. About 1920 the 

 operations were discontinued, and this large pit, of numerous rami- 

 fications and varying depths, was left exposed. Water then collected 

 within it and submerged and killed the plants that had become 

 established at the base and part way up the slopes. Those plants 

 that were growing on the sides of the excavation, above the level of 

 the water of the lake thus formed, are still present. 



In January, 1941, in preparation for using the iron deposits 

 again, the emptying of the water from this pit by pumping was be- 

 gun, and it was almost completed by the middle of June. This mine 

 presented the rather unique spectacle, then, of an emptied lake, the 

 bottom composed largely of clay and silt, and it was remarkably free 

 of aquatic plants or their remains. The previous water level was 



