170 



reason why the sister nucleus in the ventral canal-cell is so 

 difficult to see. 



In three instances spermatozoids were seen in the neck and 

 venter of the open archegonimn, and twice a spermatozoid was 

 seen in the nucleus of the egg, but there were no other stages 

 obtained, so that the details of the nuclear fusion could not 

 be followed. It probably, however, is much the same as that 

 described by Shaw foi- Onoclea. (The Fertilization of Onoclea, 

 Ann. of Bot., XII: 261—285, 1898). In the mature egg-cell 

 the nuclear reticulum is often decidedly contracted, but whether 

 this is normal or the result of reagents can not be said. 



THE EMBRYO. 



A special effort was made to obtain embryos, as both Lang 

 and Bruchmann were unable to procure the earlier stages of 

 the development of the embryo. Indeed, Lang figures but a 

 single somewhat advanced stage in 0. pendulum. Bruchmann 

 succeeded in obtaining two-celled stages, and a single more 

 advanced embryo of 0. vulgahun, and he also describes and 

 figures several stages of the young sporophyte. Mettenius's 

 figures of the embryo of 0. peduncidosum are not satisfactory, 

 but he shows correctly sections of the young sporophyte after 

 it has broken through the pro thallium. 



In 0. moluccanum where most of the prothallia develop 

 sporophytes, the small number of young prothallia that was 

 available made it impossible to obtain a series of young em- 

 bryos. A single one of tw^o cells (Fig. 116) and one older 

 embryo were all that could be found. The young sporophytes, 

 however, were found in a sufficiently early stage of develop- 

 ment to make clear some very important points bearing on 

 the structure of the young sporophyte. In this species the 

 further growth of the gametophyte is stopped by the develop- 

 ment of the sporophyte, and only rarely is more than one 

 sporophyte formed. 



In 0. pendulum a fairly complete series of embryos was 

 obtained, and the development was followed quite satisfactorily. 



