PKEFACE vii 



fungi, it now signifies less than formerly whether the 

 Rusts are regarded as related to the Ascus Fungi or the 

 Basidium Fungi. As will be seen in Chapter XIII we 

 still hold to the theory that their relationship is some- 

 what closer to the former than the latter. 



For many years it has been evident to us that the 

 apocarpous Flowering Plants must be regarded as primi- 

 tive and that from these the syncarpous forms arose. 

 Moreover the apopetalous preceded the apetalous 

 flowers, the latter being derived from the former by a 

 simplification of the flower structure. The flowers of 

 willows, oaks, elms, nettles, etc., are quite simple, but 

 they are not primitively so: they have been simplified 

 from more complex structures, and are to be associated 

 with the latter, rather than given place near the beginning 

 of the phylum. 



The diagrammatic illustrations used in this book are 

 similar to those used on our lecture room blackboards. 

 We have felt that in a textbook involving laboratory work 

 elaborate drawings were unnecessary and often subject 

 to grave abuse. 



It is scarcely necessary to-day to insist that this book 

 requires a botanical laboratory; nor is it necessary to 

 give "forms" to be followed by the student in his labora- 

 tory work; for it may be assumed that no one will attempt 

 to use this book who has not himself received training in 

 a good laboratory. We have purposely suggested many 

 more laboratory exercises than can be performed by the 

 ordinary student, affording the teacher a large list from 

 which he may make his own selection. A few suggestions 

 here as to this laboratory work may not be out of place, 

 as follows: (1) Have each pupil prepare his own speci- 

 mens, as far as possible; only in a few special cases should 

 he make use of specimens prepared by some one else. 



