456 Miscellaneous. 



solution, which appears to me to be more in accordance with the 

 facts than the preceding. 



As a first example I shall take Metzgeria /areata. The antheridia 

 occur in involucra which are almost entirely closed and are situated 

 themselves on the lower surface of the frond. When the mother- 

 cells of the antherozoids have ceased dividing, the middle part of the 

 membrane surrounding them soon dissolves ; each cell is then com- 

 pletely free, only surrounded by a very delicate membrane, which 

 will afterwards disappear. The nucleus, which was at first central, 

 approaches the surface of the cell without changing in form or 

 dimensions. At the same time all round the cell, following a great 

 circle which touches the now excentric nucleus, a delicate thread of 

 protoplasm is differentiated, becomes homogeneous and brilliant, 

 and is coloured only with great difiieulty by the ordinary reagents of 

 the protoplasm and nucleus. This is the first indication of the forma- 

 tion of the antherozoid. It is to be observed that, at this period, 

 the nucleus has not notably changed in form. We cannot there- 

 fore say that the nucleus alone forma the antherozoid by becoming 

 elongate and slender. It is true that the nucleus has a point of 

 contact with the filament ; but by treatment with ha^matoxylin the 

 colourless filament may be traced over the surface of the nucleus, 

 now strongly stained violet. 



This first phase of the formation of the antherozoid is of short 

 duration, and appears to me to have hitherto escaped the notice of 

 observers. In a rather more advanced state the different parts of 

 the mother-cell retain the same relative positions ; but the filament 

 is thicker and more intimately united with the nucleus, the nucleus 

 itself is smaller, and the protoplasm less dense. The filament 

 therefore grows at the expense of the nucleus and protoplasm. 



Still later the nucleus seems to have completely disappeared ; its 

 substance has been entirely employed in enlarging the antherozoid. 

 The protoplasm also has almost completely disappeared ; we see 

 only a colourless space in the midst of the ring formed by the 

 antherozoid. The direct observation of this stage of development 

 led some authors to suppose that the nucleus disappeared and that 

 the protoplasm then became condensed at the periphery of the cell 

 to form the antherozoid. Soon afterwards the ring breaks, the 

 filament elongates itself and becomes more slender, and gradually 

 acquires the form of the adult antherozoid. It is only at this 

 period that the two cilia appear at one of its extremities. 



The antherozoids of the other Hepaticai that I have studied 

 (Badula complanata, Frullania dilatata, and Alicularia scaJaris) are 

 formed exactly in the same way as those of Metzgeria f areata. As 

 these different species belong to groups pretty distinct from each 

 other there is reason to suppose that the mode of formation of the 

 antherozoids is very uniform in the family Hepaticaj. I hope, 

 however, to extend my observations to a greater number of species 

 and to publish figures which are necessary for the completion of such 

 descriptions as those which I have just given. 



The technical processes which I have employed in my observa- 

 tions are those which are ordinarily adopted in the investigation of 

 the nucleus. To obtain good results, however, I have been obliged 



