OUR INDIGENOUS FLORA AND FAUNA. 205 



to some extent protect other birds, and has therefore, at any 

 rate, that advantage. 



It is very remarkable, considering how long we have lived 

 on this globe with other animals and plants, how little we know 

 about them ; and yet there is intense interest in unravelling the 

 secrets of nature. 



I do not allude to difficult problems which require physical 

 laboratories and observatories, nor to those which can only be 

 solved by technical study. The formation of the blood, for 

 instance, is still a mystery ; and it is certainly an extraordinary 

 thing, considering the great importance of blood in the animal 

 system, that we do not yet know how or where it is produced. 

 There are many other questions of the same kind which might 

 be mentioned, but which, though of great importance, hardly 

 came within the range of such a Society as our own. 



Even, however, as regards the habits and life of our com- 

 monest animals and plants, there are still an immense number 

 of interesting problems remaining to be explained and solved. 



Perhaps the commonest of all English plants is Pleurococcus 

 vulgaris, the little alga or seaweed which covers the stems of 

 trees, palings, and other woodwork of a similar character with a 

 coating of green. It consists of small rounded cells, sometimes 

 quite separate, sometimes grouped together in little packets of 

 two, four, or eight. These divide and subdivide, and multiply 

 in this manner. But obviously this is only a part of the life- 

 history of the plant. Like the rest of its family it probably, at 

 certain times and under certain conditions, produces spores; 

 but all this part of its life-history is quite unknown. In the case 

 of the common mushroom, again, the spores are of course 

 enormously abundant, and yet nothing is known about their 

 germination. 



Peas, beans and other leguminous plants almost invariably 

 have swellings or tubercles on their roots. These are supposed 

 to be produced by bacteria, and when such tubercles are present 

 great quantities of nitrogen are accumulated. An important 

 result of this is that leguminous crops are supposed actually to 

 enrich the soil. In Germany, in many places, the yellow lupine 

 is especially grown for no other purpose but to be ploughed in 

 and thus improve the soil for other crops. These bacteria are 



