24 LETTERS TO MARCO iv 



concerned in the garden, may be easily 

 known and remembered as lilies and their 

 kind ; with a few exceptions, all that are not 

 lilies are Exogens. There is another class 

 which comprises the mosses, lichens, etc., 

 but they are more or less permanent plants, 

 and do not have to struggle through the 

 earth in the spring. 



The exogenous and endogenous methods 

 of pushing through the soil are exactly like 

 the two ways a lady threads her needle : 

 either with a screwed and pointed end as 

 in the case of cotton, or with a loop as in 

 the case of worsted. The exogen pushes 

 through with a loop, whilst the endogen 

 pierces through with a point. 



The loop method is the most interesting 

 to watch, and I will take that first. You 

 know, I dare say, that plants, and indeed 

 most livings things, 1 grow quickest in the 

 dark ; warmth and darkness being very con- 

 ducive to growth, as on the other hand cold 



1 As, for instance, babies. 



