ACHLYA. 



6 ] 



ACHLYA. 



fused throughout the tube, only densest 

 where it hes on the wall, increases in quan- 

 tity and "travels up" into the end of the 

 tube, becoming accumulated there, giving 

 it a brownish colour and at the same time 

 causing its distension, so that the upper part 

 of the tube acquires a clavate form, rounded 

 off above. At this time the dense mass of 

 contents thins off gradually below into the 

 protoplasm of the lower part of the tube, 

 but a sharp line of demarcation is soon 

 formed, by the division of the primordial 

 utricle, followed by the production of a sep- 

 tum, which shuts off this clavate joint as the 

 sporange. Simultaneously with the for- 

 mation of the septum, a little projecting 

 pouch or beak is developed at the summit, 

 or sometimes a little below this, on one side; 

 and the contents, becoming still more con- 

 densed, again apply themselves as a thick in- 

 vestment on the wall, leaving a lighter space 

 in the middle of the cavity. Inequalities, or 

 nodular protuberances, are soon observable 

 in this layer, and it speedily becomes broken 

 up into numerous little isolated portions, the 

 individualization of these commencing at the 

 summit of the sporange and becoming com- 

 pleted gradualtyfrom above downwards. The 

 end-cell is now a clavate sporange filled with 

 numerous polyhedial or globular new " pri- 

 mordial cells," in the development of which 

 from the contents of the general mother-cell 

 no trace of nuclei or " special-mother-cells " 

 can be detected; their size is about 1-2/00 

 of an inch. These primordial cells, the 

 mother-cells of the gonidia, have clearly- 

 defined outlines, but are still connected to- 

 gether by a gelatinous substance, in which 

 they are completely imbedded, and which 

 seems to have been secreted by themselves, 

 as the entire protoplasm of the sporangial 

 parent-cell has been previously converted 

 into daughter-cells. These daughter-cells 

 then become retracted from the walls, and 

 accumulate in a dense, rather confused-look- 

 ing mass in the centre of the sporange ; en- 

 dosmose of water through the now bare cel- 

 lulose wall of the sporange seems to exert 

 a pressure upon them, and also on the wall 

 itself, which finally bursts at the process or 

 beak mentioned above, and the daughter- 

 cells nearest the opening are shot out with 

 some force, the rest following, but gradually 

 more quietly. There is no independent 

 motion of the contents, or jerking of the 

 daughter-cells, before this emission of the 

 latter ; on the contrary, while in the spo- 

 range, they adhere so closely that their shape 



is scarcely distinguishable, and it is only 

 when the greater portion have escaped, that 

 it is perceived that the pressm'e had caused 

 them to assume a spindle-shape. As the 

 emission of the daughter-cells goes on, those 

 escaping first are only removed so far as to 

 make room for their successors, and the 

 whole remain adherent together as a glo- 

 bular mass or " capitule" seated on the apex 

 of the sporange; they re-assume, more or 

 less completely, the spherical form, by de- 

 grees, after they have escaped from the spo- 

 range ; those which can expand freely be- 

 come globular, those pressed upon by their 

 fellows become polj^hedral. At the time 

 of emission, these daughter-cells exhibit a 

 double line at the circumference, which 

 seems to indicate the thickness of the ' pri- 

 mordial utricle.' Soon after the expulsion 

 another delicate line is detected external to 

 these, and this indicates a newly produced 

 envelope, which becomes thicker with age, 

 and after a certain time can be colom'cd blue 

 by sulphuric acid and iodine, which demon- 

 strates its composition of cellulose. Appli- 

 cation of a strong acid is necessary for this 

 purpose. 



The globular head of daughter-cells re- 

 mains for two or three hours attached upon 

 the summit of the empty, colom-less spo- 

 range. Then these minute cells emit their 

 contents by a lateral orifice, giving birth, 

 each of them, to a zoospore or active goni- 

 dium. Neither the motion nor the appear- 

 ance of the cilia follows the expulsion imme- 

 diately, but takes place after the gonidia have 

 increased somewhat in size and acquired an 

 ovate form. The duration of the motion 

 lasts from a few seconds to a few minutes, 

 after which the spore sinks to rest and begins 

 to germinate. The gonidia possess no cellu- 

 lose membrane while in motion, but acquire 

 one when they come to rest and germinate. 

 The cilia are two in number, and arise from 

 the point which first emerged from the pa- 

 rent vesicle, and which at all periods exhi- 

 bited a lighter tint, indicating a vacuole in 

 the protoplasmic mass. If the expulsion of 

 the gonidia is prevented, as occurs some- 

 times when the plant is kept under the 

 pressure of a glass slide, in too little water, 

 in microscopic investigation of it, the go- 

 nidia germinate within then cell-membranes, 

 which, instead of discharging active zoo- 

 spores, emit germinating prolongations, just 

 like those issuing from the single germina- 

 ting gonidia. These spread out here in all 

 directions from the globular capitulum, still 



