No. 526] SEXUAL REPRODUCTION IN GTMNOSPERMS 597 



known. Objections to such a suggestion are easily 

 raised, but the question seems worth investigation, es- 

 pecially since little is known of the behavior of the 

 chromatin during the mitosis by which two sperms are 

 produced from the body cell. 



Except in the cycads and Ginkgo, there are no motile 

 sperms in living gymnosperms, but, in our opinion, the 

 transition is not so abrupt as some writers believe. The 

 definitely organized male cells of such genera as Sequoia 

 and Thuja look very much like the young sperms of a 

 cycad immediately after the division of the body cell, 

 the principal difference being the absence of the ble- 

 pharoplast, which is such a conspicuous feature in the 

 development of the sperms of cycads and Ginkgo. In re- 

 gard to the several genera with well-organized male 

 cells, the statement is made that there are no structures 

 which could be interpreted as the vestiges of blepharo- 

 plasts, but the figures accompanying the various ac- 

 counts are not convincing and it seems entirely possible 

 that vestiges may yet be found. 



According to all the accounts, either as expressed in 

 the text or to be inferred from the figures, the body cell 

 in Taxeae, Taxodicw and Cupresseas gives rise directly to 

 the male cells, there being no formation of sperms within 

 sperm mother-cells. The accounts may be correct, but 

 it must be remembered that a competent observer de- 

 scribed just such a condition in one of the cycads, where 

 it is now known that the sperms are formed within sperm 

 mother-cells from which they are afterwards discharged. 

 Among the Coniferales, the well-organized male cell is 

 found in the Taxaceas, Taxodiea? and Cupressefe. 



In the rest of the Coniferales, which means the Arau- 

 carieae and Abieteae, there are no organized male cells, 

 but only male nuclei lving free in the cvtoplasm of the 

 body cell, and this cytoplasm not always" slmrplv limited 

 from that of the pollen tube. Accompanying these male 

 nuclei there are often structures which might be inter- 

 preted as the vestiges of blepharoplasts. According to 

 some observers, one of the male nuclei is smaller than the 



