BRIEFER ARTICLES 



PARTHENOGENESIS IN PINUS PINASTER 



■ 



(with seven figures) 



In the course of an investigation on the life-history and development of 

 the embryo of the cluster pine, Pinus pinaster Soland., it has occasionally 

 been noticed that in some ovules containing proembryos in all stages 

 of development either no trace of pollen tubes could be seen in the nucellar 

 cap, or the tubes only extended through a part of the nucellus and no 

 nuclei could be found in them. This strongly suggested the occurrence of 

 parthenogenesis, but might have been due to imperfect preparations. There- 

 fore, in 1908, collections were made about every twelve hours during the 

 time when the archegonia mature, in the hope of obtaining more satisfactory 



evidence. 



Great care was used in fixing and imbedding this material, and the 

 following fixing agent has been found more satisfactory than any other, 



including chromacetosmic mixtures. 



The 



Picric acid, saturated solution in 50 per cent, alcohol, ioo cc ; corrosive 

 sublimate 5*™; glacial acetic acid s cc . This fixing agent is mentioned by 

 Chamberlain, 1 and I have to thank Mr. A. J. Ballantine for suggesting 

 its use. Cedar-wood oil has been found much superior to xylol to P re « de 

 the infiltration with paraffin, as mentioned by Miss Ferguson ('04). 

 stains used have been Delafield's hematoxylin, much diluted and allowed to 

 act for several hours, and Flemming's safranin gentian-violet orange- 

 combination. The first named shows nuclear details more sharply than 

 the triple stain and is only equalled in this respect by Haidenhain's iron 

 alum hematoxylin, which is more troublesome to use and in no way supe^ 

 rior. In other respects the methods used have been those generally emp oye 

 in cytological work. ,, . 



The evidence obtained shows clearly that parthenogenesis occasiona } 

 occurs, and the most conclusive preparations are shown in Jigs. 1 a " 



The points which seem to prove satisfactorily that the oosphere deve op 

 without fertilization taking place are as follows: _ , 



1. Although the oosphere nucleus has divided or begun to divi ^ ^ 

 pollen tube has not yet reached the archegonium and still contains 

 sperm nuclei (figs. 1, 2). 27 . 2 68- 2 8o. 



1 Chamberlain, C. J., Oogenesis in Pinus Laricio. Bot. Gazette 



ph. 4-6. 1899. 



Botanical Gazette, vol. 47] 



[406 



