Febeuaey 23, 1900.] 



SCIENCE. 



307 



A new type of branching in the leafy Sepaticce : 

 Dk. a. W. Evans, Yale University. 

 (By invitation.) 



According to Leitgeb, who made a thor- 

 ough study of the various kinds of branch- 

 ing exhibited by this group of plants, his 

 so-called ' Endverzweigung ' or ' terminal 

 branching ' always occurs in the ventral 

 half of one of the lateral segments cut off 

 from the apical cell. In the curious Masti- 

 gohrywn integrifoliwn Aust. of the Hawaiian 

 Islands, this same kind of branching occurs 

 in both lateral and ventral segments, show- 

 ing that it is much less restricted than 

 Leitgeb supposed. In this case the ventral 

 branches, apparently from their place of 

 origin, are specialized as flagella. 



The geotropism of split stems : Dk. E. B. 



CoPELAND, University of West Virginia. 



(By invitation.) 



Numerous experiments show that if a 

 stem be split into two equal halves and 

 then placed in a horizontal position, the 

 lower half is stimulated to grow more 

 rapidly than the upper. As compared with 

 an erect half stem, the upper horizontal 

 half (that with the split surface downward) 

 has its growth depressed, while the lower 

 horizontal half has its growth considerably 

 more accelerated. This is what happens 

 in an uninjured prostrate stem in the exe- 

 cution of a response to the geotropic stimu- 

 lus, except that the difference in growth 

 between the halves is much greater when 

 they are separated. 



It has been held that in the geotropism 

 of stems there must be at least a transverse 

 transmission of the ' sensation,' by which 

 the halves can compare their positions ; but 

 in view of the behavior of the isolated half- 

 stems this argument is obviously invalid. 



Some variations and correlations in the leaves 

 of trees : Miss Harriet B. Winsor, 

 Springfield, Mass., and De. W. F. Ga- 

 NONG, Smith College. 



This paper, offered as an illustration of 

 method, represented the results of an at- 

 tempt to apply statistical methods to the 

 study of an ecological problem, namely the 

 factors determining the length of petioles 

 and the size and shape of the leaf. The 

 studies are to be continued. 



Perennation in the stem of Lycopodium alopecu- 

 roides: Dr. J. M. Macfarlanb, Uni- 

 versity of Pennsylvania. 

 The author pointed out that in this 

 species the branch extremities begin to dip 

 into the ground in autumn by what has 

 been proved to be geotropic growth. This 

 portion becomes colorless, greatly loaded 

 with starch, and bears leaves that become 

 specially modified from those of the normal 

 green type. When the perennating part 

 is fully developed it is a hook-like depres- 

 sion which lies dormant until the succeed- 

 ing spring. By succeeding apogeotropic 

 growth it again reaches the surface and as- 

 sumes its usual development. 



Of special interest is the fact that the 

 above peculiarity is being gradually ac- 

 quired, for while a large proportion of 

 plants show it, a few that may grow pro- 

 tected in loose sphagnum or under water 

 only show it to a feeble extent. 



The phytoecology of the Bay of Fundy salt 

 marshes : Dr. W. F. Ganong, Smith Col- 

 lege. 



At the head of the Bay of Fundy occur 

 great salt marshes which bear a remarkably 

 varied vegetation, showing transitions from 

 the usual salt marsh to fresh- water bogs. 

 The reclamation of the marshes for cultiva- 

 tion brings in another element, and all 

 transitions may be found between the salt 

 and the reclaimed marsh. These transi- 

 tions of conditions afford an unusual oppor- 

 tunity to investigate some phases of the 

 dynamical relationships of plants to their 

 surroundings, and the author has attempted 

 to work out this problem in ecology. The 



