

LOTSY, CURRENT THEORIES OF EVOLUTION. 389 
which I am showing you (Fig. 1) have not arisen by any process 
of variation atall, but by hybridizing Gennaeus argentatus and lineatus 
with one another, while the less complete series of intermediates 
between lineatus and Horsfieldii has been obtained from hybrids 
between these latter species. These experiments have been carried 
out by Professor ALESSANDRO Guia! of Bologna, to whose kindness 
I owe these feathers. 
It cannot be too strongly emphasized that observation can reveal 
nothing but diversity while the experiment must be called in, to 
‘decide the cause of the observed diversity. 
LINNAEUS, with his admirably penetrating mind saw this already, 
but, unfortunately, did not act up to the principle he himself 
enunciated. Within his species he did distinguish two kinds of 
varieties: varietates levissimae and varietates tout court. The first, 
which now we would call modifications, did not, according to his 
view, concern the systematist because they are of a merely transient 
nature: varietates levissimae non.curat botanicus, the latter, on the 
other hand, deserve all consideration: varietates attente insbiciantur, 
because they transmit their peculiarities to their progeny. As an 
example of varietates levissimae he gives different plants modified 
by wind, drought etc; as one of varietates: the different forms of 
cabbages, such as green cabbages, red cabbages, Brussels sprouts 
etc., all belonging to his species Brassica oleracea, which came 
true to seed. 
LINNAEUS consequently rightly distinguished between non-trans- 
mittable vartetates levissimae, our modifications, and transmittable 
vartetates. 
The giving of such similar names to so fundamentally different 
categories of individuals was, of course, apt to cause confusion 
and has caused it, even in LINNAEUS’ mind, to such an extent that 
— forgetting the distinction he himself had made — we find him 
speaking of a form ,mutata a causa accidentali, caloris, ventis 
etc. as of a varietas, while, of course, he should have referred to 
it as to a varietas levissima. So it came about that the distinction 
between transmittable and non transmittable variability was forgotten 
and that all, merely observed, deviations from the supposedly 
typical individuals within a linneon were called varieties, while of 
course the observation of such differences within a linneon or 
