348 BOTANICAL GAZETTE [apeil 



cycads, screw pines, palms, orchids, figs, ebonies, the gorgeous Atnherstia, 

 and many other tropical trees grow luxuriantly. 



All in all, Jamaica probably offers the botanist as great a variety of 

 tropical conditions within a day's walk of Cinchona and a day's drive 

 from Kingston as can be found anywhere in an area of this size. It is 

 evident that the opportunities for the study of many kinds of botanical 

 problems are abundant at Cinchona, Hope, and Castleton. In fact, 

 there are many botanical problems of prime importance which can be 

 studied only in such environments. 1 



Any American botanist wishing to work at Cinchona may be granted 

 this privilege by the Cinchona committee, consisting of N. L. Britton, 

 J. M. Coulter, and D. S. Johnson. Inquiries for this privilege and 

 for information regarding the conditions under which it may be granted 

 should be sent to the writer. — D. S. Johnson, Johns Hopkins Univer- 

 sity> Baltimore, Md. 



CHROMOSOME NUMBER IN THE SEQUOIAS 



For some years we have been concerned with cytological studies 

 in the genus Sequoia. In particular a review of the evidence presented 



by Lawson 



pervirens 



That considerable interest attaches to this genus is obvious, and certainly 

 the information available in regard to the life history of S. gigantea is 

 meager. The present note is intended "primarily to call attention to 

 certain points which have been indicated in our preliminary studies. 

 Lawson reports that, in his material collected at Stanford Uni- 

 versity, California, the pollen grains are formed during the second or 

 third week of December, and that the pollen is shed during the first 

 week of January. 3 In our experience, extending over some three years, 

 the pollen is often mature in September and rarely is it found on the 

 tree after November. Our observations have been made on trees of 

 the same size growing in three different localities: Berkeley, Redwood 

 Peak, and Mill Valley, California. There is great variation in the 

 time of pollen shedding. Two trees standing side by side may show 

 a difference of two weeks to a month in the occurrence of this phenome- 



x For further details see Science 43:917. 1916, find Popular Science Monthly, 



January, 1915. 



The 



and embryo of 



setnpervirens . Ann. Botany 18:1-28. 1904. 



a Shaw, W. R., Contribution to the life history of Sequoia sent pervirens. BoT. 

 Gaz. 21:332-339. 1896. 



