LUPiNOSis. 493 



liave been known to follow its use, but were not understood 

 Others speak of lupin seed meal as excellent for young calves. 



A bitter principle, probably alkaloidal, seems to be character- 

 istic of the various species. We have certain knowledge in the 

 case of two at any rate, viz., Liqnnus albus d.nd Zupinus angusti- 

 folius. From the seeds of these an alkaloid has been isolated, 

 called lupanine. Bitter to the taste, it is said not to be hurtful 

 to man, but experimentally to be poisonous to frogs. 



The Root Tubercles of Lcguminosce. — The Leguminosae are well 

 termed "nitrogen collectors," for they collect quantities of 

 nitrogen, and this withoiit making the soil poorer, but, on the 

 contrary, leaving it richer in nitrogen at the end of their growth. 

 Experimentally it is known that in the absence of nitrogen in 

 the soil they can flourish. 



The Leguminosse, then, possess some means of supplying them- 

 selves with nitrogen, means denied to the generality of plants, 

 which are dependent almost entirely for their nitrogen on the 

 nitrates in the soil. The LeguminoscC, almost alone among 

 plants, are able to make use of free nitrogen of the air or soil, 

 and this power is associated with tiie presence of nodules or 

 swellings in their roots. These swellings vary in size in the 

 different species. Examination by the microscope of a transverse 

 section through such a swelling shows a multiplication in num.ber 

 of the cells of the ground tissue of the root. In these cells there 

 can be seen, in addition to the protoplasm, a number of bacteria. 

 These bacteria pass into a form to which the name " bacteroid " 

 has been given. These bacteroids expose a large surface to 

 the air, and make use of the free nitrogen preparatory to 

 its being combined into such forms as the plants can absorb 

 and use. We have here a useful partnership between a lower 

 plant and a higher, between bacteria on the one hand and the 

 leguminous plant — bean, clover, lupin, &c. — on the other. The 

 bacteria are first of all nourished by the plant, and later the 

 contents of the bacteroids are absorbed by the plant. 



If a soil be sterilised and the germs thus killed, no tubercles 

 will be formed until the soil be in some way " microbe seeded." 



If this disease were due to a ptomaine or toxiue generated by 

 the action of the bacilli upon the constituents of the plant, the fact 

 that lupinosis is only induced in animals grazed on poor pastures 

 could be easily understood, but conditions identical with those 



