HYBRIDS AMONG THE AMARYLLIZ: AND CACTACE, 405 
HYBRIDS AMONG THE AMARYLLIIA AND CACTACEA, WITH 
SOME NOTES ON VARIATION IN THE GESNEHRACHEA AND 
THE GENUS SENECIO. 
By A. Worst ey, F.R.H.S. 
WHETHER the Mendelian hypothesis accounts for all the variations noted 
in hybrid and cross-bred plants and their descendants, or only for some 
such variations, is, I think, an open question. Certainly in mongrels and 
florists’ plants generally it has been ascertained that colour variations follow 
Mendelian law to some extent. 
But colour is only one character among many. It is a character which 
is by no means constant even in species, and is one in which we are sure 
of noting variable results among garden plants even without the advent 
of foreign pollen. How variable such results may be is well known to 
horticulturists, and I have tabulated some of these results for purposes 
of comparison. (See Cineraria, p. 413). 
As to form, it does not appear that the Mendelian hypothesis has . 
been demonstrated. In some cases the results have been in accord there- 
with, but in others diverse and even contradictory results have been noted 
by various observers. 
Now, it is perfectly clear that if, subsequent to cross-fertilisation, 
mutations occur according to any definite rule and uninfluenced by any 
external conditions whatever, such mutations have their cause and their 
continuation solely in the act of cell-union ; then (in such a case) we may 
trace back mutation in its entirety to this one act, and to the subsequent 
growth of protoplasm. Moreover, we must greatly modify the accepted 
theory of plasmic homogeneity. For if from one union of diverse cells, 
wholly uninfluenced as to essential character by any subsequent 
external conditions, must spring diverse individuals differing from each 
other in essential characters of a predetermined kind; then, clearly, we 
must contemplate heterogeneity of protoplasm; and must realise that, 
notwithstanding aspectual similarity, there must exist in such cases an 
essential heterogeneity or diversity of protoplasm such as exists between 
different species. Not only so, but we must also admit that the incidence 
of such heterogeneity is governed by Mendelian law. 
If we maintain that every permanent character * is acquired by cell- 
union and in no other way, then it is clear that an individual in which 
every cell was normal could only produce, if self-fertilised, absolutely 
* That is, a character capable of being reproduced in offspring by any sexual 
process. 
