VOLUME XXXVI 



I 



NUMBER 4 



1 



I 



t 



4 



Botanical 



Gazette 



OCTOBER, igo2 



} 



1 



t 



A MORPHOLOGICAL STUDY OF THUJA. 



CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY. 



XXXIX. 



W. J. G. Land. 



(with plates vi-vni) 



Material for the study of Thuja occidejitalis L. was collected 

 in the vicinity of Chicago during the late spring and early summer 

 of igoi. A few collections were made in June 1902, in order to 

 determine whether the time of fertilization varies in two suc- 

 cessive seasons. The trees were visited twice each week and 

 material fixed immediately after' the remov^al of the branches. 

 Branches were also kept in the laboratory, some having water 

 pressure applied to the cut end of the stem, and collections were 

 niade daily, AH the material from which illustrations are made 

 was taken from a single tree, the most vigorous one to be found. 

 Collections were made from many other trees in order to deter- 

 mme whether the periods of the various stages of development 

 are the same in different individuals of the same locality. Little 

 difference could be observed. 



For stages before the formation of archegonium initials i 

 per cent, chromo-acetic acid was most useful, but for later stages 

 It was not so good, as it was not possible to secure rapid pene- 

 tration of the tissues even when used at a temperature of 80^. 

 A modification of Carnoy's formula was found to give the best 

 results for fertilization and succeeding stages, although many 

 fixing agents were given a thorough trial. None of the fixing 



249 



