146 



SCIEXCE-GOSSIP. 



circles round the stem, and, in the older parts, 

 spread in all directions, whilst in the younger 

 parts the filaments are disposed more or less 

 horizontally. The filaments are much branched, 

 and are formed of cells either cj-lindrical or 

 narrowl}- barrel-shaped. Towards the circumfer- 

 ence of the tufts may be roundish bodies, darker 

 in colour and formed of short cells. These are the 

 fruit-bodies or c\-stocarp3. The further structure 

 may best be seen if a small plant or a portion of 

 a larger one is mounted on a slide and crushed bj- 

 steadj- pressure on the cover-sUp. Using a high- 

 power, 4-inch, for instance, the stem is seen made 

 up of longitudinal rows of cells of two forms. 

 In the centre the cells are very large and form a 

 single row, and around these are a number of rows 

 of shorter, much narrower, cells, constituting a 

 covering or kind of cortex to the larger central cells. 

 The stems and branches do not at first possess this 

 cortex, which is only formed on them as they 

 increase in age. The way in which the cortex is 

 formed is rather curious, and is very similar to the 

 origin of the cortex in Chara. The cortex of Chard 

 is formed by branches arising from the lower parts 

 of the leaves and growing upwards and down- 

 wards, uniting with similar growths above and below, 

 to form a covering around the long central cells. 

 The formation of the cortex of Batrachospermum 

 differs only to the extent that the out-growths 

 from the lower parts of the leaves proceed in 

 one direction, from above, downwards. Tracing 

 the stem upwards, all stages in the formation of 

 this cortex may be seen : the lower segments 

 with a complete investment, above these segments 

 arotmd which the do%vn-grovving filaments have not 

 yet imited, and higher up segments with but the 

 rudiments of the investments. 



If the cells of the stem are traced upwards, their 

 length is seen to gradually lessen, and finallj- they 

 become disc-shaped, terminating in a cell sUghtly 

 longer and with a rounded free extremity. This is 

 the apical cell, by means of which, di\ision occur- 

 ring at the lower end, elongation of the stem takes 

 place. Sometimes the apical cell is obscured by 

 the surroimding filaments, and then an extremity 

 of one of these may be tsken for it, but it can 

 usually be found by tracing up the stem and 

 careful focussing. In tracing np the stem there 

 will be noticed lateral growing-points repeating 

 the structure of the main axis, and the origin of 

 the tufts of filaments, leaves as they may be called, 

 arising from short ceUs given off from the upper 

 extremities of the large stem- cells. 



Shotild an entire plant be vmder %-iew that 

 has carefiilly been removed from the surface 

 on which it grew, the root should be noticed, 

 consisting of long narrow rows of cells. These 

 filaments, tmlike the other cells of the plant, do 

 not possess colouring-matter. They spread on 



the surface of the stones, etc., attaching the plant 

 to these. 



The sexual organs should now be studied. A 

 plant may bear male organs (antheridia) only, or 

 female organs (procarps) only. In the latter case 

 it usually happens that when bearing ripe fruit 

 or cystocarps they will also bear antheridia 

 in addition. It is very difficult to get a view of 

 a procarp before it has been fertilized. After 

 fertilization it undergoes a process of growth that 

 renders it easily recognizable. A procarp is formed 

 from the terminal cells of a branch of a leaf. It 

 consists of two parts, each with a different function. 

 A larger, more conspicuous part, the trichogyne, 

 with which the male fertUizing cell becomes united, 

 and below this, separated by a constriction, a 

 smaller part, the carpogone. It is hardly likely that 

 a procarp will at once be identified, but if attention 

 is given to cystocarps in various stages of develop- 

 ment, proceeding from the more to the lesser 

 developed, the trichogynes will be seen as club- 

 shaped or spindle-shaped organs projecting from the 

 latter. The rounded body at the extremitj- is not 

 a part of the trichogyne, but is a male fertilizing 

 cell that has become fused with the trichogyne. 

 The male organs, antheridia, are roundish cells 

 produced at the extremites of branches of the 

 leaves. They are borne singly or two together 

 upon the supporting cell, and, besides their shape, 

 are distinguished by the light colotu: of their 

 contents. For the purpose of effecting fertilization, 

 the protoplasm, or contents of each antheridium. 

 becomes Uberated into the surrounding water. It 

 is now a spermatium or male fertilizing cell. 

 It does not possess a coating of cellulose, 

 and is unprovided with any means of propul- 

 sion through the water. Between the times of 

 being set free and of coming into contact with a 

 trichogyne, each spermatitun forms around itself 

 a firm coating of cellulose. When it comes into 

 contact with a trichogyne, it becomes firmly 

 attached to this. At first the surfaces that are 

 appHed to each other are but small, but, apparenth^, 

 the male cell becomes compressed to an extent and 

 dra^vn down on the trichogyne. After a time the 

 spermatium puts out a very short broad tube that 

 penetrates the wall of the trichogyne, and the 

 portion of cell-wall in contact with the tube dis- 

 appears. There is now an open channel between 

 the male cell and the trichogyne, the width of 

 which varies, being greater or smaller. It is often 

 the case that more than one spermatium becomes 

 applied to a trichogyne, and then the most frequent 

 numbers are two or three, though as manj- as seven 

 spermatia may attach to one trichogj^ne. In these 

 cases of more than one spermatium becoming 

 attached to a trichogyne, the usual position of the 

 cells is as follows : one male cell occupies the 

 extreme apex, and the others are disposed on the 



