March 31, 1905.] 



SCIENCE. 



507 



Nymphcea from a paper now in press. The 

 embryo in its development and mature form 

 is typically dicotyledonous in Nymphcea, 

 though it lacks a suspensor in Nuphar. 

 The primary root quickly perishes, and the 

 stem becomes tuberous immediately above 

 the epicotyl. The root tip of Nuphar re- 

 sembles that of Zea mats, but in Nymphcea 

 it is like that of Papilionacea^ and Cucur- 

 bitaeeae. The vascular bundle of the root 

 of Nymphcea is radial and polyarch. The 

 scattered bundles of the stem of Nuphar 

 and some Nymphceas give place to a dis- 

 tinct vascular cylinder with leaf-gaps in the 

 primitive Nym. mexicana. In no case are 

 the bundles oriented as in monocotyls. 

 From each leaf three traces come into the 

 stem, one central and two lateral; they 

 differ from many dicotyls only in pos- 

 sessing a transverse commissure connect- 

 ing the three traces. No secondary 

 growth of the bundles takes place in any 

 part of the plant. In this and in the 

 polyarch roots and in the short life of the 

 primary root are the only similarities be- 

 tween Nymphcea and the monocotyls. 

 These are best explained as adaptations 

 to a long established aquatic habit. 



An Exploration of a Peat-forming Lake 

 (illustrated) : Dr. G. P. Burns, Univer- 

 sity of Michigan. 



Perhaps no line of ecological research 

 shows the deficiency of present methods 

 better than the work on peat bogs. These 

 are cited as examples of 'xerophytic' habi- 

 tats and there are many theories offered 

 explaining the presence of plants growing 

 in them. 



These theories differ widely. Nor can 

 we expect them to do otherwise under pres- 

 ent methods. 



The first problem of the ecologist must 

 be to gather and record facts, but these 

 must be submitted, as far as possible, to 

 experiment before attempting to determine 



their final value. As in all other lines 

 ( f botanical research, experimental work is 

 indispensable. 



A study of the plants in peat-forming 

 lakes near Ann Arbor, Mich., shows that 

 they are by no means all xerophytes. With 

 xerophytes are found many plants whose 

 structui-e is either mesophytic or hydro- 

 phytic. 



In fact, within a circle whose diameter is 

 only a few feet may be found plants be- 

 longing to all three of these groups of 

 plants. 



Peat bogs then, as such, can not be called 

 'xerophytic' habitats. 



W. F. Ganong, 



Secretary. 



SCIENTIFIC BOOKS. 

 Die Gletscher. By Dr. Haxs Hess. 



Braunschweig, Friedrich Vieweg und Sohn. 



1904. Large 8°, pp. xi + 426. 



This is the only important woi-k on glaciers 

 that has appeared since the well-known book 

 of Professor Heim was published in 1885, 

 and it is of the same general excellent char- 

 acter. Dr. Hess has had a good preparation 

 for writing the book by his training as a 

 physicist, which is of much importance in the 

 actual study of glaciers, and by many years 

 of careful observations and measurements of 

 the glaciers of the Oetzthal in conjunction 

 with Professor Finsterwalder and Dr. 

 Bliimcke; and he makes many references to 

 the very important observations which they 

 have made, especially on the Vernagt and 

 Hintereis glaciers, which have thrown so much 

 light on the theory of glacier motion. 



The plan of the book does not differ essen- 

 tially from that of Professor Heim. The 

 matter is presented inductively; first assem- 

 bling the observations and facts and then giv- 

 ing the theories to account for them. The 

 large amount of work which has be^n done in 

 the last twenty years makes such a work very 

 desirable and Dr. Hess has collected all the 

 material and has presented it in a most at- 

 tractive and interesting form. 



