300 XXII. REPRODUCTION OF 



abundant contents. Nuclei are not visible without special means ; 

 small chromatophores are numerous. In ripening, the contents 

 collect into small balls, each with one, rarely two, reddish-brown 

 chromatophores. 



Between the sterile and the fertile hairs are found elliptic 

 structures, the female sexual organs, the oogonia, which vary in 

 size according to their stage of development, but ultimately attain 

 to very considerable dimensions. The larger ones are coloured 

 yellow- brown by small chromatophores ; the abundant contents 

 make them almost opaque, but with care it can be determined 

 that they contain eight oospheres, with flattened contact surfaces. 

 The smallest are unicellular, colourless in their periphery, trans- 

 parent, with a brown fleck in the middle due to the aggregation of 

 the chromatophores. Older stages show from two to eight such 

 flecks, and finally cleavage planes are formed simultaneously 

 between these flecks, dividing the contents of the oogonium into 

 eight fairly symmetrically arranged oospheres. After complete 

 division, the brown colour is uniformly distributed through the 

 contents of the oospheres. If the section has passed through the 

 point of insertion of an oogonium, it will be seen that it is situated 

 on a short unicellular stalk. In almost all sections through ripe 

 conceptacles single oogonia will be torn off from their stalks. If 

 such oogonia are observed for a time, an outer layer of the wall 

 is seen to rupture at the apex, and the oospheres protrude, sur- 

 rounded by an inner layer. This inner layer swells strongly in 

 water, especially at its upper part, and gradually becomes dif- 

 fluent and unrecognisable, and the oospheres are distributed in 

 the surrounding water (Fig. Ill, E). The oospheres round off, 

 are devoid of membrane, and in the centre of each a clearer fleck 

 is recognisable. If ripe antheridia are similarly broken off, after 

 a while the contents are extruded, surrounded by an inner sheath 

 (Fig. Ill, B). After a time the contents escape in the form of 

 small pear-shaped bodies, but in these cases movement is not 

 usually seen. 



Material hardened in alcohol cuts much better, and if stained 

 with haematoxylin, gives beautiful figures, which amplify in not 

 unimportant points the results obtained' from fresh material. 

 Thus, nuclei can be detected in the rudiments of oogonia, in 

 number increasing, by repeated bipartitions, from two to eight ; 

 then follows the simultaneous formation of dividing planes, each 

 oosphere having a central nucleus (Fig. Ill, D). The nucleus 



