ioo EXPERIMENTAL EVOLUTION LECT. 



Among flowers the same variability obtains. Colour 

 may be different, but there are also important varia- 

 tions of a morphological order, and many botanists 

 have pointed out the more interesting cases in all 

 parts of the world. Maxwell Masters has collected 

 a number of them in his Teratology, and Udo 

 Dammer has added many in the German edition 

 of this work; more recently, Dr. O. Penzig, of 

 Genoa, has collected all known cases anew, in his 

 important Pflanzen-Teratologie (1890). In this book, 

 of which only the first half has yet been pub- 

 lished, we find a very complete list of teratological 

 cases, of cases of variation in all parts of the plants, 

 and of every sort, so that I may refer to this book 

 once for all, as concerns all plant variation. Some 

 idea of its value may be gathered from the fact that 

 1 66 large octavo pages are filled up with the mere 

 titles of papers referring to variation, and that the 

 whole work is devoted strictly to facts, so that it may 

 really be considered as a list as complete as possible 

 of all departures from the normal types. Of course 

 variations of floral structures are numerous, and cases 

 abound in this work, but I prefer referring, as an 

 instance, to a case which is not noted by Dr. Penzig, 

 and which is of great interest, as it concerns import- 

 ant variations observed in the floral structures of one 

 and the same individual plant, a Tradescantia virgi- 



