LIFE HISTORY OF PINUS 63 



sperms, Strasburger ('6g-^2) was unable to demonstrate, satis- 

 factorily to himself, the character of the cells found in the 

 pollen-tube in Pinus, and he has not recently investigated the 

 male gametophyte in the Abietinece. Coulter ('97) described two 

 sperm-cells which were of the same size until within the arche- 

 gonium. Blackman ('98) stated that each sperm-nucleus was 

 clearly seen in the pollen-tube surrounded by its own cytoplasm, 

 but he did not figure them.^ Chamberlain ('99) figured the 

 sperm-nuclei, in Pinus Lartcto, of equal size in the pollen-tube, 

 and showed them lying together in the cytoplasm of the tube. 

 Not having seen these cells within the archegonium before the 

 conjugation of the sexual nuclei, he accepted Coulter's state- 

 ment for the growth of one of them after their entrance into the 

 egg. According to Coulter ('00) the " male cells in pines " are 

 alike in size. The same figures are reproduced by Coulter and 

 Chamberlain ('01). 



As stated by the writer in 1901, two sperm-cells have not been 

 observed in any of the pines which I have studied ; but the 

 sperm -nuclei, which are of unequal size from a very early date, 

 remain, while in the pollen-tube, surrounded by a common cyto- 

 plasmic body (figs. 109-112, plate X; 113-118, plate XI, and 

 119-120, plate XII). As Strasburger ('92) observed, the larger 

 nucleus is always ahead, that is, on the side nearest the apex of 

 the pollen-tube. The smaller nucleus remains close against the 

 upper boundary of the cytoplasm, and suggests the condition in 

 Cycas (Ikeno '98) and Ginkgo (Hirase '98), where the stalk- 

 nucleus is forced entirely out of the cytoplasm surrounding the 

 generative nucleus. In the case of the smaller sperm-nucleus in 

 Pimis, the action is not carried to so great an extent. Webber 

 ('01) has recently shown that such an interpretation as that re- 

 corded above for Cycas and Ginkgo is not true as regards the 

 stalk-nucleus in Zamia. One very interesting preparation which 

 I have obtained shows the smaller sperm-nucleus in advance of 

 the larger (fig. 114). Here it will be seen that the entire order 

 of arrangement has been changed, the stalk-cell and the tube- 

 nucleus being above the sperm-cell. But this abnormal arrange- 

 ment is onl}'- apparent, for it was found that the ^^^ which had 



* See note at close of Appendix. 



