150 IOWA ACADEMY OF SCIENCES. 



Mention should be made of the splendid work of Coulter and 

 Rose on the anatomical characters found in the leaves of coni- 

 fers and their value in the recognition of species. A subject 

 referred to long ago by Dr. George Engelmann. The work of 

 Pax on the anatomy of Euphorbiaceje, Trecul and others on 

 the stems of many plants. 



It will not be necessary to give other references; the litera- 

 ture is quite extensive. More work should be done along this 

 line. We should study the biological relations and the conse- 

 quent peculiar anatomical structures of plants. It is a field 

 full of interest. Theo. Holm has called attention to the value 

 of this kind of work in studying our flora. 



Ganong, in a recent paper with reference to biology and 

 morphology (Present Problems in Anatomy, Morphology and 

 Biology of Cactacese, Bot. Gazette, Vol. XX, p. 180), says: 

 "As to the tissues, it is enough here to say that the character- 

 istic xerophilous appearances are strong cuticle, thick epidermis, 

 perfect cork, sunken stomata, collenchymatous hypoderma, 

 deep palisade layers; great development of pith and cortex, 

 which consists of large, round, splendidly pitted water- storing 

 cells, often containing mucilage * * * ." The whole sys- 

 tem conforms closely to the external form and follows its 

 morphological changes. We notice this especially because the 

 same thing holds true in other plants outside Cactacece, especi- 

 ally grasses. Great difference occurs between such plants as 

 are habituated to humid climates and those occurring in a dry 

 climate. This offers, indeed, a great field for investigation. 



ANATOMICAL STUDY OF GRASSES. 



Theo. Holm has done well in calling attention to some ana- 

 tomical characters of North American Gramineae. In speaking 

 of the studies which had been made he says: "The impor- 

 tance of studies of that kind was very clear; they not only fur- 

 nished additional and often even more reliable systematic char- 

 acters, but the extended study of anatomy into wider fields than 

 ever before, until anatomy has become one of the most impor- 

 tant modern lines of botanical science." He emphasizes the 

 importance of internal structure, as it will give a striking illus- 

 tration of the physiological life of the plant. It will not be 

 necessary here to refer to earlier writers on the subject; suffice 



