HOMOTYPOSIS IN TPIE VEGETABLE KINGDOM. 
3;i7 
distribution of the high degree of varialdlity in the broom pod. We have so far 
reached notliing hut the soii on the Hartstongue fern with anything like sucli a high 
coefEcient of variation. We might expect, if Mr. Adam Sedgewick’s view were 
correct and great variation meant small intensity of heredity, that homotyposis, of 
which heredity is only a special case, would also he small if variation were large. 
But we find nothing of the kind. The resemblance of undifterentiated like organs 
reaches the value '4155, fully equal to that of the phDirp of the ash, which have less 
than half the variability of broom pods. This value is close also to the AOOO given 
hy the Ancestral Law of Heredity for the degree of resendolance between brothers. 
In the next place this normal behaviour as to the degree of resemblance of like 
organs is associated with a variability in the individual which amounts to upwards of 
90 per cent, of the racial varial)ility. It is impossible to form standard deviations 
for groups of 10, but if the reader will reduce any array of the above table to the 
number 10, rejecting all fractions of unity, he will obtain (|uite fair samples of 
what I actually found in the case of individual })ods. I think we may feel faiidy 
confident that the variability of a race is not in inverse })roportion to either its 
heredity or its homotyposis. 
It will be seen that broom, so far as it goes, supports the view held by Darwin 
that the number of ripe seeds is a measure of individual constitution. At the same 
time the question of self-fertilisation arises. Would completely self-fertilised plants 
exhibit full homotyposis ? May not outside influences—wind, shaking due to visits 
of insects or other causes of a random character—be also needful for the ripening of 
the seeds even in the case of self-fertilisation ? Again, can we always suppose that a 
plentiful visitation will take place in the case of all cross-fertilised plants ? I must 
confess that the value for the homotyposis found in the case of broom did not suffice 
to remove all my doubts as to any character depending on fertilisation being a 
suitable one for the determination of the intensity of homotyposis. The subject, 
however, is one of such great interest that it deserves an independent and fuller 
treatment than can be provided here.* 
V. Cross-homotypic Correlation. 
(“21.) Mushroom (Agaricus campestris).—A more complete study was now made of 
two species—the mushroom and the ivy. We found some difficulty in discovering 
two easily measurable or countable cliaracters in one organ, neitlier of which was 
largely influenced hy the growth of the organ or the age of the organism. In select¬ 
ing an organ in tlie mushroom, I was guided by the desire to take a sinqile organism, 
and an organ upon which fertilisation had no influence. The gill of the mushroom 
seemed to satisfy to some extent these conditions. Had we been able to grow our 
own mushrooms we might have succeeded in taking them all at the same stage of 
* This has been to some extent provided in an Appendix to this memoir, added since its completion. 
VOL. CXCVII.—A. 2 X 
