TRANSACTIONS OF SECTION D. 747 



is perfectly iuactive. I might quote many similar facts, if iicccssaiy. Thus, sul- 

 phuric acid, sulphate of copper, &c., are strongly attractive. Certain bodies 

 which are onlv moderately hygroscopic, as white soap, lose or gam moisture 

 according to the degree of 'dampness uf the surrounding atmosphere; and in the 

 lirst case they repel Phycomyces, in the second they attract. 



The sensibility of Pliycoviyces is, in fact, so great that it may_ actually be used 

 as a reagent to test the existence of hygroscopic power. Having noticed that 

 camphoi-'very distinctly attracts the fiiameuts, and thymol does not (although 

 both of these substances have a deleterious action on them), 1 could anticipate 

 that camphor is hygroscopic— a fact which, though unknown to chemists, was 

 confirmed bv careful weighing. 



Lastly, the theory may be tested in another way. Differing from lilaments ot 

 Thycomyces, roots of higher plants are positively hygroscopic. Then, as might be 

 expected, they bend away from iron instead of being attracted by it. 



All these experiments succeed also in a saturated atmosphere, which shows 

 that hydrotropism is not due, as generally admitted, to differences in the hygro- 

 metric" state of the air. But the discussion of this point, as well as certain deduc- 

 tions relative to the physical phenomenon of hygroseopicity, must be reserved for a 

 detailed paper on this subject. 



To sum up the general results : the apparently mysterious action ol iron on 

 riiyavmyces is nothing but a matter of hydrotropism ; and hydrotropism itself 

 (negativ'e or positive) is the bending of a vegetable organ towards the points, not 

 where it will find a minimum or maximum of moisture, but where it will, within 

 certain limits, transpire most or least. 



5. Nutes on the Morpholuffy of the Spore-hearing Memlers in Vascular 

 Cryptogams. By Professor F. O. Bowek, F.Ii.S. 



6. Notes on an Aposporous Fern Seedling. By C. T. Dkuest, 



A Cliytridian ParasUic on C'ydops' Eggs. 

 By Professor M. Hautog, D.Sc. 



8. On ilte Arrangement of tie Buds in Lemna Minor. 

 By Miss Nina P. Layakd. 



The object of this paper was to illustrate the order of budding f )llowed by 

 specimens, the development of which was watched and figured by the writer, from 

 that of a single frond until it had increased to a connected colony ot six. 



The=e observations seemed to point to the fact that this duckweed, as a general 

 rule, produces two buds only, the first being usually from the right side, and the 

 second from the left ; thougli exceptions occur in both cases, and there are other 

 difficulties which must be cleared away before any such law can be looked upon 



as established. . . , „_ j i i 



The following table gives the result of the examination ol 4/o duckweea 

 groups taken from an outdoor aquarium on July :32, 1892 : — 



Single duckweeds , . . . ti . , . 



C l.-)0 of which were bearing 



Duckweeds in pairs .... 232 s' buds on the lidit side, 



L and 82 on the left. 



„ in groups of three . . 120 



four . . 92 



fi^e • • 17 



six . . 7 



eight . . J_ 



Total . . 475 



