K. Miyake, Contribut. to the Fertiliz. and Embr^'Ogeny of Abies balsamea. 141 



In varioiis stages of proembrj'o formatiou aud even after the 

 proembryo is completely formed, two to four or sometiines as many 

 as six nuclei are often found in the upper part of the egg-cypto- 

 plasm (Figs. 35, 38). Some of these nuclei may probably be de- 

 rived from the second sperm-nucleus , the tube-nucleus and the 

 nucleus of the stalk-cell. It seems possible that one or two of them 

 may be traced back to the nucleus of the ventral canal-cell. 



A possible case of double fertilization. 



An interesting- case which may be interpreted to represent 

 double fertilization was found in one preparation. As illustrated in 

 Fig. 46 , the fertilized nucleus is apparently in its second division. 

 Three spindles are found in the original boundary of one of the 

 two segmentation- nuclei. Two of them are found side by side m 

 the Upper portion and the other one lies in the lower part of the 

 nuclear area somewhat separated from the upper two. Of the upper 

 two spindles one which appears in the first two sections of the 

 series seems to have more than twelve chromosomes (Figs. 46a— 46b), 

 and the other which is found in the fourth and the fifth sections 

 has approximately twelve chromosomes (Figs. 46d— 46e). The number 

 of chromosomes in the lower spindle which is seen in the fourth and 

 fifth sections seems to be less than twelve. 



It is not safe to give any definite interpretation to such abnormal 

 figures without fuither evidence. It seems possible, however, that 

 this might represent a case of the fertilization of one of the two 

 segmentation-nuclei by the second sperm-nucleus. One of the two 

 upper spindles with approximately twelve chromosomes may possibly 

 represent that of the second sperm-nucleus, the other with more 

 than twelve chromosomes might have been formed from more than 

 half of the chromatic substance of the segmentation-nucleus , which 

 moved up towards the conjugating second speim - nucleus, while the 

 small remanining part of the clu^omatic substance developed into the 

 chromosomes of the lower spindle. In other words, when the second 

 sperm-nucleus conjugated with one of the two segmentation-nuclei, 

 all of the chromatic substance of the latter did not accumulate near 

 it, but a smaller part was left behind, and thus beside the spindle 

 belonging to the sperm-nucleus two other spindles were formed having 

 an unequal number of chromosomes. The spindle of the other seg- 

 mentation-nucleus seems to have approximately twenty-four chromo- 

 somes. 



In the upper part of the same archegonium two abortive 

 mitotic figures were observed. In one of them spindle-fibres are 

 well developed, but no chromosomes can be seen (Fig. 46g). The 

 other has a rather small spindle, and a group of chromatic substance 

 is found near each pole (Fig. 46 f). Two figures probably belong to 

 the tube-nucleus and the nucleus of the stalk-cell. 



Summary. 



1. The number of archegonia in a Single ovule varies from 

 one to four, the most common number being two. The neck 

 of the mature archegonium usually consists of three or four tiei-s 



