322 MONOGRAPH OF THE BRITISH SPKCIES OF EUPHRASIA. 



but I would refer botanists to the monograph itself for the con- 

 sideration of the subject in all its bearings. We have only eleven 

 or twelve indigenous species, but to explain the phytogeny of these 

 I find it necessary to review most of the European species with 

 which our own are so intimately connected. This will more easily 

 be understood when it is taken into account that we have in our 

 indigenous species representatives of all the European groups 

 adopted by Prof. Wettstein.* The monograph is written in 

 German, and many may not have access to it, hence my excuse 

 for an attempt to deal with this somewhat difficult subject. 



Part I. 



Morphology, Evolution, and Formation of Species. 



In the first paragraph of the monograph Prof. Wettstein gives us 

 an insight into his method of working. He there states that it 

 is by deep study of the areas of distribution of individual forms that 

 a knowledge of the history of their evolution is to be obtained, and 

 later on he says again that the best way of gaining an insight into 

 the history of the development of the forms of a polymorphous 

 group of plants is to study the geographical range of each individual 

 form. Having sufficient data as regards the European forms, he 

 has found it possible to define their areas of distribution. With 

 regard to extra-European forms he has not attempted a similar 

 study, as we do not as yet possess sufficient data for the purpose. 



For the determination of species Prof. Wettstein has had special 

 regard to their phytogeny or race-history, as well as to their stability 

 and distinctness of character ; he notes that the development of 

 species has been so varied that they are neither equal in rank nor in 

 age ; i. e. that their development has occurred in different ways and 

 at different epochs. A feature in the monograph is that varietal 

 names are not multiplied. The way in which the species vary is 

 noticed, and the varietal names given by authors in their descriptive 

 works are alluded to and sifted. 



Elementary Organs ; the Epidermis and its Processes. — Prof. 

 Wettstein estimates the character of the hairs to be of great specific 

 importance in this genus ; much more so than I had deemed them 

 to be. They are found on the stem, the leaves, the bracts, the 

 calyx, the corolla, and the capsule ; they are of two kinds, viz. 

 glandular and eglandular. The eglandular hairs may consist of 

 one or of several cells placed end to end, and the hairs gradually 

 narrow to a point ; they are found on the stem, leaves, bracts, 

 calyx, corolla, and capsule. In many cases where they may seem 

 to be absent it will be found that they are one celled, and so reduced 

 in size as to be perceptible only through a lens. The glandular 

 hairs are also of two kinds. They may consist of one cell tipped by 

 a gland, or of several cells placed end to end, the last tipped by a 

 gland, and this distinction is of great importance. The third kind 



* It is a matter of considerable satisfaction that the groups proposed by 

 me in a former paper on Enphnisia (Joiini. Bot. 1884, jip. 161-168), though 

 more numerous, naturally fall into those adopted by Prof. Wettstein. 



