THE HIGHER CRYPTOGAMIA. 189 



tion. The latter often retains its original spiral form, and 

 remains attaelied to the interior of the vesicle within which 

 the spermatozoon originated (PI. XXIV, fig. 14"-*). The 

 forward motion of the spermatozoon is always accompanied 

 by a rapid rotation round the axis of the spiral, and follows 

 the direction of this spiral, which is sometimes a right- 

 handed, sometimes a left-handed one.* 



When the prothallinm has become two-lobed, and has a 

 deep indentation on its fore-edge, the cells of that portion 

 of it which lies immediately behind the indentation, divide 

 by means of septa parallel to the surface of the prothal- 

 linm. This division is repeated two or three times, always 

 in the lower one of the newly-formed cells. By this 

 means a flat cushion of cellular tissue is formed on the 

 under side of the prothallinm. On its hinder part, new 

 antheridia continue to be formed for a considerable time. 

 The archegonia are produced at the fore -part adjoining the 

 indentation. t 



The mother-cell of an archcgoniimi is distinguished from 

 the adjoining cells by an abundance of finely granular 

 mucilage, and by the presence of a larger less flattened 

 nucleus. The adjoining cells just mentioned are rich in 

 chlorophyll : their contents are clear like water, and they 

 have a small lenticular nucleus adherent to the cell- wall. 



* The statements of authors with regard to the form of the spermatozoa of 

 Ferns, their number, their nature, and the mode of attachment of their cilia are 

 in some respects very contradictory. Their discoverer, Niigcli, makes no 

 mention of cilia. Lesczyc-Sumiuski in his account of the development of Terns 

 (Berlin, ISIS) speaks of a few large cilia as attached to the clavatc fore end 

 of the spermatozoon of Pteris serrulala. This is an error, as the spermatozoa of 

 the latter species are similar to those of Asplcnium. Schacht (' Linnsea, 5 Td. 

 xxii) considered the vesicle in which the spermatozoon is produced, and which is 

 often dragged along by the whip-shaped end of the latter, to be an essential 

 portion of it. This accounts for the difference between his observations and 

 those of other botanists. He considered the vesicle to be the fore end of the 

 spermatozoon and that the hinder part preceded the narrower ciliated coils 

 when in motion. Thurct's statements ('Ann. desSc. Nat,' iii ser., vol. 11) 

 agree with mine except that he does not mention the tail of the spermatozoon. 



f In order to justify the application to the organs of Terns, of an expression 

 hitherto only used when speaking of the female organs of mosses, I must refer 

 to a subsequent part of this work ; where I endeavour to show that the fruit 

 (capsule and fruit stalk) of a moss answers to that which in ferns (taken in the 

 most extended sense) is simply called the plant ; and that the prothallium of 

 the fern is equivalent to the moss-stem, bearing antheridia and archegonia, 

 which is often much branched. 



