122 MR. HENFREY ON THE DEVELOPMENT 



its cavity. The same takes place upwards and downwards, and thus the antheridium, 

 when examined in this state, seems to consist merely of one large cell (figs. 21, 22 & 26), 

 with rather thick walls consisting of a double membrane (figs. 24, 25). 



While in this expanded condition the entire structure increases in size, and the contents 

 of the central cell become more granular. After a time faint lines can be detected run- 

 ning through the protoplasm (fig. 21), and these soon display themselves more clearly as 

 the boundaries of square isolated masses of the protoplasm (figs. 22 & 25), the nascent 

 sperm-cells. Around each of the little masses thus isolated a membrane is formed. It 

 was impossible to ascertain whether the parent-cell was first divided into a number of 

 square partitions, by cross walls, thus producing " special parent-cells," for the sperm-cells, 

 like those formed in the development of pollen-grains, the original partitions subsequently 

 becoming dissolved to set free the cells thus originally connected together ; or, whether 

 the protoplasm was simply entirely broken up into a number of isolated portions, each of 

 which secreted a membrane and thus formed a free cell ; but I incline to believe that the 

 latter was the fact, and that the same occurs in the completely similar case of the produc- 

 tion of a number of closely packed endosperm-cells, in the embryo-sac of many Phanero- 

 gamia, as in the Cruciferse and Scrophulariacese*. However this may be, the result is the 

 production of a large number of free cellules, filled with mucilaginous protoplasm (figs. 26, 

 34), of a light yellowish colour, becoming gradually more and more granular. As these 

 cellules, at first squarish, enlarge, they become spherical, and by their expansion distend 

 the parent-cell and disguise the existence of the annular cell surrounding it. Their num- 

 ber, in well-developed antheridia, seems to be between thirty and forty, probably never 

 exceeding the latter number. 



The free cellules, the sperm-cells, become more and more opake and granular, and after 

 a time spiral lines may be detected in them, while still within the parent-cell in the 

 antheridium (figs. 35 & 36). At this time the antheridia may be burst very easily by pres- 

 sure (fig. 36), and the sperm-cells which escape can be observed in all stages of develop- 

 ment, until a spiral fibre can be clearly seen, coiled up in the interior. Specimens lying 

 in water, under the microscope, now frequently exhibit a movement of the contents of the 

 sperm-cells, they swell up, and the spiral lines are seen to change their position. Very 

 often the bursting of the sperm-cells takes place within the antheridium, and the sperma- 

 toxoid becomes free (fig. 38). But usually, and apparently normally, the cellules are dis- 

 charged entire from the antheridium. This occurs by the splitting of the line of junction 

 of the lenticular cell crossing the antheridium with the lateral cell, at first at one side and 

 then usually all round, but sometimes it remains attached by a small portion (fig. 48). 

 By this circumscissile dehiscence the cavity of the antheridium is freely opened, as when 

 the lid is removed from a box. The sperm-cells begin to escape as soon as the dehiscence 

 commences, and a large portion of them have often made their exit before the lid has 

 completely opened. 



As the opening of the lid gives a vent to the contents of the distended central cell, the 

 tubular enveloping cell exerts a pressure inwards by striving to regain its original form, 

 and as the sperm-cells are discharged, the side-walls of the central cell come back into 



* I have observed it in Lathreea Squamaria most distinctly. 



