358 THE ORCHID REVIEW. [DECEMBER, 1909- 
The lecturer explained that the earliest idea that two characters were 
associated in a Mendelian pair, one of which happened to be dominant and 
the other recessive, had now been modified. The allelomorphic pair, as he 
put it, was not composed of a pair of homodynamous characters or values, 
one of which was dominant and the other recessive, but of the presence of 
a single character and the absence of it. The presence was dominant and 
the absence recessive. The lecturer continued that this ‘‘might and even 
ought to appear to have far exceeded the limits of legitimate hypothesis 
spinning but experiment proved its correctness.’ I was just about to say 
that it looked as if the pair were only one after all; but I had not got to 
the experiment. Unfortunately the subject was not an Orchid, so I must 
summarise the details. It related to characters found in the seed coat of 
two varieties of pea, maple-spotting in one, purple-coat in the other, and 
these characters are termed M and P, their absence m and p. The two 
varieties were crossed together, and the hybrids then self-fertilised in the 
usual way. Most of the self-fertilised seeds showed both characters, but 
some showed one only, some the other only; the two latter being in fairly 
equal numbers. 
The lecturer remarks: ‘‘ I well remember the excitement with which I 
opened the dry pods of the plants of this F2 generation. . . . I had 
examined many plants before I found one bearing the m p character (t.¢., 
the two absences together], and as I had not a very large number of plants, 
and this character is only expected to occur once in every sixteen 
individuals, I became afraid that 1 might not see one. But I did ultimately 
obtain two such plants. And well do I remember the interest with which I 
looked on these peas in which the two units, absence of M and absence of 
P, were associated in one individual.” The lecturer explains that the 
presence and absence hypothesis may have been put forward to explain one 
or two outstanding difficulties, but this conception has now supplanted the 
original form of it. 
Perhaps we may be allowed to call it Neo-Mendelism, and it now 
remains to explain a case of my own where all the absences were dominant 
together—presence being recessive. This also was unfortunately a pea, not 
an Orchid. A good many pods had been opened without success, but at 
length the desired combination was found. The pod was burst open 
—it was an exciting moment—and there was nothing in it! 
But the principle is applicable to Orchids; indeed cases are not 
uncommon where the capsule opens of itself and is found to contain— 
NOTHING ! ARGUS. 
