584 TRANSACTIONS OF SECTION K. 



growth, and from the lamina. Crystalline osazones have been found in the 

 cortical colls, the sieve-tubes, and the hyphae in both species, and particularly at 

 the time of formation of the new lamina in L. digitata. Some of the crystals in 

 the latter plant very closely resemble those yielded by Maltose, but their exact 

 identity is at present unknown. 



This production of osazones in the hyphce and in the sieve-tubes after treat- 

 ment with Senft's reagent affords experimental evidence in support of the con- 

 ducting and storing function hitherto assigned to these elements mainly on account 

 of their structure. 



2. The Structure and Function of the Boot-nodules oj Myrica Gale. 

 By Professor W. B. Bottomley, M.A. 



The root-nodules of Myrica Gale arise as modifications of normal lateral roots 

 which by branching form the characteristic ' clusters ' covered with rootlets 

 growing out through the end of each nodule or branch. The branching is due 

 to the outgrowth of lateral roots, and not to dichotomy of the apex of the 

 primary nodule, as in the root-nodules of Cycas, Alnus, and Ela?agnus. 



In transverse section a young nodule shows a central tetrarch vascular 

 cylinder surrounded by an endodermis of cells filled with oil drops. The cor- 

 tical tissue contains (a) numerous 'bacterial cells,' in which the bacteria can be 

 seen by treatment with Kiskalt's Amyl Gram stain; and (b) cells filled with oil 

 drops. Towards the apex of the nodule ' infection threads ' can be seen pass- 

 ing from cell to cell, and the whole nodule is protected on the outside by two 

 or three layers of cork cells. 



When the growth of the nodule is nearly complete the end of the stele, sur- 

 rounded by a few cortical cells, grows on and out from the apex of the nodule, 

 and forms a thin rootlet. Around the end of the nodule usually three (occa- 

 sionally only two) branches arise as lateral swellings which grow and repeat 

 exactly the structure of the primary nodule, with a rootlet growing out from 

 the apex of each branch. By repeated branching the typical ' cluster ' nodules 

 are formed. 



Pure cultures of the bacteria from the ' bacterial cells ' show small rod-like 

 organisms identical in appearance and structure with Pscvdomonas radicicola, 

 the organism found in all leguminous nodules, and give a definite fixation of 

 nitrogen when grown in Erlenmeyer flasks :— 



Control flask ...... 0-53 mgr. N. per 100 c.c. 



Inoculated flask ...... 2-58 ,, ,, ,, „ 



Young Myrica plants grown in pots in soil deficient in nitrogen flourished well 

 if possessing nodules, if without nodules on their roots they soon died. 



Evidently the root-nodules of Myrica are concerned with the assimilation 

 of atmospheric nitrogen, as are the root-nodules of Cycas, Alnus, Elaeagnus", and 

 Podocarpus. 



3. Some Effects of Bacteriotoxins on the Germination and Growth of Plants. 

 By Professor W. B. Bottomley M.A. 



An aqueous extract of well-rotted manure or fertile soil, obtained by treating 

 100 grin, of manure or soil with 500 c.c. of isotonic salt solution and filtering 

 through a Pukall filter, has an injurious effect on the germination of seeds and 

 their further growth in sand, even when supplied with normal food-solution. 

 This inhibitory effect of the extract can be destroyed by boiling. The harmful 

 effect is due to the presence of certain bacteriotoxins, probably of the nature of 

 toxalbumoses, formed by the activities of the decomposition and denitrifying 

 bacteria in the manure or the soil, and by heating the toxic influence is destroyed 

 and the substance rendered available as a nutrient. 



Experiments with germinating seeds of mustard, turnip, tares, and barley 

 give support to this theory. Seeds germinated in pots containing sand moistened 

 with (a) distilled water, (6) saline solution, (c) raw extract, (d) boiled extract 

 showed that the raw extract almost prevented germination and the subsequent 



