218 FRESH-WATER ALG^ OF THE UNITED STATES. 



in size and soon being cut off from the parent-cell by a partition, forms a complete 

 cell, the starting point of a new branch. If this cell has been formed alone, with- 

 out companions, it is the beginning of a main branch, and divides after a very brief 

 period transversely, the new cell thus arising in a little while itself divides, and so 

 the process goes on until the axis of a large branch, similar to the parent axis is 

 developed, and which, like the parent axis, increases only. by a division of the end 

 cell and longitudinal growth of the central ones. 



When a glomerulus is to be formed instead of a single pouch, a number appear 

 around the upper end of a cell, and become cut off as new cells. Each of these 

 is the starting point of a new row of cells, which not only grows, at least up to 

 a certain point, by the division of the end cells, but which also gives rise to a 

 large number of branches in a way precisely similar to that in which it itself was 

 developed, i. e., by the formation of little lateral protrusions, &c. These secondary 

 branches have a life-history similar to that of the branch whose offspring they are. 

 They continually give origin to new branchlets in the way just described, which 

 branchlets themselves produce fresh offshoots, and so it goes on until at last the 

 forest of branchlets making up the dense glomerulus is evolved. It has been 

 just stated that the original axis of the main filament or any branch is composed 

 of a single simple series of large cells ; when an old Batrachosperm is placed under 

 the microscope, however, it is at once evident that the axis is in reality formed of 

 such a series lying in the centre and covered over and often hidden by numerous 

 longitudinal series of smaller cells. These latter do not belong to the original 

 axis, but are secondary additionsnto it, and arise in this way. "Whilst a glomerulus 

 is being developed certain of the basal cells of its constituent branches give origin 

 in the usual manner to branchlets, which, instead of growing outward to form a 

 part of the glomerulus, grow upwards or downwards, closely hugging and finally 

 enveloping the original axis, and at last forming a distinct cortical layer to it. 



Very frequently in well-advanced Batrachosjoerms there will be seen scattered 

 among the glomerulus large, round, firm, dense balls composed of a great number of 

 small closely-attached cells. These are the reproductive bodies. According to H. 

 Graf zu Solms-Laubach (Botanische Zeitung, 1867, p. 161), they are the result of 

 sexual reproduction, and are developed from aniheridia and trichogonia (female 

 organs) in the following manner : — 



The antheridia are small roundish cells full of a colorless protoplasm, which is 

 remarkable for the very numerous bright granules which it contains. They occur 

 either scattered or in groups, and are placed upon the upper ends of peculiar ovate 

 cells, also filled with a colorless protoplasm. Most frequently there is a single 

 antheridium to the basal cell, sometimes two ; the latter number appears never to be 

 exceeded. When matured, the antheridia open and allow their contents to escape 

 in the form of roundish or flattened bodies, which never, as far as known, acquire 

 cilia, and have, therefore, no power of spontaneous motion. These bodies, which 

 are believed to be spermatozoids, are unprovided with anything like an external 

 membrane, and are composed of protoplasm identical with that in the antheridium. 



Whilst these changes are occurring, certain cells in other localities are being trans- 

 formed into female organs, to which our author applies the name of Trichogonia. 



