XII EQUISRTINEM 453 



tion of the exact orij^in of tlic ]^rimary meristem ancl its relation 

 to the secondary ones found in llie Ijranches is nuicli to be 

 desired 



JefTrey finds in E. arvcnsc, E. hicmalc, and E. Uuiosum, that 

 the neck canal cell usually divides longtitudinally, and compares 

 it with the divisions in the archegonium of Lycopodium 

 phlcginaria. This division may take place in 7i. tchnatcia, but 

 is exceptional. It may be mentioned that a similar flivision has 

 been observed in Marattia Douf^Iasii. 



Each archecfonium stands between two lobes, the one from 

 • whose base it has itself developed, and the next younger one. 

 As these lobes in vigorous prothallia grow to a large size, and 

 branch, this gives the prothallium an extremely irregular out- 

 line, recalling very much that of Anthoccros piinctatus or A. 

 fiisiformis. These branching lobes are not to be confounded 

 with the branches of the prothallium body due to the dichotomy 

 of the archeo-onial meristem. These latter are alwavs short, 

 and project but little compared to the secondary branching lobes 

 produced from them. The entrance of the spermatozoids and 

 the changes subsequent to fertilisation seem to be exactly the 

 same as in Ferns. 



The prothallia are normally dioecious, but this is not ex- 

 clusively the case. To a certain extent the external conditions 

 influence the production of males or females, as in the Ferns, 

 and unfavourable conditions of nutrition tend to increase the 

 r^ proportion of the former. 



According to Hofmeister (i) the number of archegonia 

 upon vigorous prothallia varies from twenty to thirty. His 

 statement that this exceeds the number of antheridia in the 

 larger male prothallia is not confirmed by Buchtien, who found 

 as many as 120 of the latter in some cases. 



Usually more than one archegonium is fertilised, Hof- 

 meister having found as many as seven embryos upon a single 

 prothallium. He does not state how many of these develop. 

 The embryo corresponds closely to that of the Ferns, and has 

 been carefully described by Sadebeck (6). 



The Embryo 



The fertilised &gg grows until it completely fills the ventral 

 cavity, and its granular contents become more separated, and 



