94 REMINISCENCES. [Ch. IV. 



of white thread to distinguish the trays in which they lay. 

 When he had to compare two sets of seedlings, sowed in tho 

 same pot, he separated them by a partition of zinc-plate ; and 

 the zinc-label, which gave the necessary details about the 

 experiment, was always placed on a certain side, so that it 

 became instinctive with him to know without reading the label 

 which were the " crossed " and which the " self-fertilised." 



His love of each particular experiment, and his eager zeal 

 not to lose the fruit of it, came out markedly in these crossing 

 experiments — in the elaborate care he took not to make any 

 confusion in putting capsules into wrong trays, &c. &c. I 

 can recall his appearance as he counted seeds under the simple 

 microscope with an alertness not usually characterising such 

 mechanical work as counting. I think he personified each 

 seed as a small demon trying to elude him by getting into the 

 wrong heap, or jumping away altogether ; and this gave to tho 

 work the excitement of a game. IIo had great faith in instru- 

 ments, and I do not think it naturally occurred to him to doubt 

 the accuracy of a scale, a measuring glass, &c. He was 

 astonished when we found that one of his micrometers differed 

 from the other. He did not require any great accuracy in 

 most of his measurements, and had not good scales ; he had an 

 old three-foot rule, which was the common property of the 

 household, and was constantly being borrowed, because it was 

 the only one which was certain to be in its place — unless, 

 indeed, the last borrower had forgotten to put it back. For 

 measuring the height of plants, he had a seven-foot deal rod, 

 graduated by the village carpenter. Latterly he took to using 

 paper scales graduated to millimeters. I do not mean by this 

 account of his instruments that any of his experiments suffered 

 from want of accuracy in measurement, I give them as 

 examples of his simple methods and faith in others — faith at 

 least in instrument-makers, whose whole trade was a mystery 

 to him. 



A few of his mental characteristics, bearing especially on his 

 mode of working, occur to me. There was one quality of mind 

 which seemed to be of special and extreme advantage in leading 

 him to make discoveries. It was the power of never letting 

 exceptions pass unnoticed. Everybody notices a fact as an ex- 

 ception when it is striking or frequent, but he had a special 

 instinct for arresting an exception. A point apparently slight 

 and unconnected with his present work is passed over by many 

 a man almost unconsciously with some half-considered explana- 

 tion, which is in fact no explanation. It was just these things 

 that he seized on to make a start from. In a certain sense 



