192 Prof. J. B. Farmer and Mr. J. LI. Williams. 



cytoplasm also changes, and tends to assume a more definitely radiat- 

 ing character, the lines starting from the nucleus as a centre. 



We observed, not unfrequently, rather large cells in which two- 

 nuclei of equal size were lying in close juxtaposition. These cells, 

 with their nuclei, answer exactly to the description given by Behrens 

 of the fertilisation stage in plants examined by him. We are unable 

 however, to accept his interpretation, for, in the first place, the 

 series of fertilisation stages which we have observed, and have 

 briefly described above, in no way correspond with the appearances 

 described by him, and secondly, because these large cells (Behrens 

 himself emphasises their size) are seen in material to which no 

 antherozoids have had access. Furthermore, the average size of the 

 young oospores is not obviously greater than that of the oospheres. 

 themselves. We regard the bodies in question as representing 

 abnormal developments of oogonial cells, and not as being in any 

 way concerned with fertilisation. Moreover, we have occasionally 

 observed one cell in the divided oogonium, much larger than the rest, 

 to contain two, or even sometimes three, nuclei, and these nuclei are 

 then always close together. These facts have led us to reject 

 Behrens' account of the process. 



A very large number of experiments were made, in order to deter- 

 mine, if possible, the time which elapsed between the addition of 

 the antherozoids to the oospheres and the first division of the spore. 

 A short summary of different sets of observations on Ascophyllum is 

 given in the subjoined tables. 



SERIES I, Observations on Ascophyllum conducted at the Seaside, 

 (a) The antherozoids were added to the oospheres at 10 o'clock A.M. 



Lot 1. Fixed 23 hours after the addition of antherozoids. Nucleus preparing for 



division. 



2. 24 ,, Nucleus divided, rhi- 



zoid rudiment present, 

 no dividing wall. 



,, 3 & 4 32 Nucleus divided, no rhi- 



zoid, dividing wall pre- 

 sent. 



5. 36 Spore divided into about 



six cells. 



(6) The antherozoids added between 11 and 12 P.M. 



Lot 1. Fixed 24 hours after the addition of antherozoids. Nucleus divided, a few 



with rhizoid rudiments 

 and division wall. 



2. 25 ., Same result. 



3. 25 Not beyond spindle 



stage. 



4. 28 Nucleus divided, no rhi- 



zoid or dividing wall. 



