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gelatinized and swell up* on the addition of water, at the same 

 time curving outwards and leaving a wide opening for the escape 

 of the swollen mass of slime in which the antherozoids are 

 embedded. During this year I have also had under observation 

 a number of forms in which the antheridia are developed in cavi- 

 ties scattered singly along the surface of the thallus, namely 

 Riccia glanca, Pellia epiphylla, P. calycina, Aneura latifrons, and 

 Pallavicinia Flotowiana. In these forms, as in the mosses and 

 the acrogynous Jungermanniaceae, the antherozoids were found 

 to be discharged quietly, the slime containing them simply oozing 

 out of the antheridial cavities. Several times in watching under 

 the microscope living male plants of Riclla Capensis, a mass of 

 antherozoid-slime was seen to be suddenly expelled from the 

 opening of an antheridial cavity on the free margin of the thallus- 

 wing, but the force of the discharge did not send the mass to any 

 appreciable distance (only about 2 millimeters) from the opening. 

 In the majority of the Marchantiaceae, the antheridia are de- 

 veloped in groups on specialized portions of the gametophyte, 

 forming sessile or stalked receptacles, in the tissue of which the 

 antheridia are more or less deeply sunk ; each antheridium usu- 

 ally occupies a separate cavity, which communicates with a pore 

 on the outer surface of the receptacle by a long narrow canal. 

 Water is absorbed by (i) the cells of the tissue between the an- 

 theridia, (2) the cells forming the antheridial walls, and (3) the 

 antherozoid-mother-cells, all of these cells having become muci- 

 laginous. From renewed observations made this summer on 

 male plants of Conocephalum, I can fully confirm the conclusion 

 arrived at by Peirce and by King, namely, that the explosive 

 discharge of the antherozoids from the antheridial cavity as jets 

 of spray is to be attributed simply to this absorption of water by 

 the cells of the antheridium itself and those of the surrounding 

 tissue. It occurred to me to ascertain whether discharges could 

 be induced in the case of dead plants. Male plants with well- 

 developed receptacles were placed in absolute alcohol, in which 

 they were allowed to remain for periods varying from a few hours 

 to several days. They were then taken out and the receptacles 

 moistened with water by means of a camel-hair brush. In 



