MICHIGAN ACADEMY OF SCIENCE. 
31 
bv crossing was in 1STG by Dr. W. J. Beal, the first president of this 
academy. On the basis of present accomplishment we are safe in claim- 
ing, when once the improved methods are in general use, an increase 
in value of our corn crop of $300,000,000 without additional acreage or 
labor. 
The plant breeder then is a sorter and arranger rather than a creator, 
the only hope for something new seems to be in the occurrence of a 
mutation. Large changes, such as those of Oenothera used by de 
Vries, seem to be rare enough, but possibly mutations smaller in amount 
may be quite frequent. If such occurred within the extremes of exist- 
ing genotypes or of fluctuations they could be recognized only with the 
greatest difficulty, and yet might be used unknowingly by the breeder. 
It is certainly very remarkable how often the selector has started to 
attain a non-existent ideal and has got there. Nor must we lightly set 
aside the universal belief of breeders that cultural conditions induce 
heritable variations. We do not know what induces mutation but de 
Vries believes external cause to> be the more probable. 
Culture widely modifies the external conditions, crossing the internal, 
even to affecting the chromosomes of the zygote. In the garden, if any- 
where, there would seem to be a chance for permanent changes in the 
unit-charcters of the plant. When we realize the basic importance of 
variation, and our own inability to control it, some very recent experi- 
ments are of surpassing interest. These are associated in this country 
with the names of Tower and McDougal, the former working with in- 
sects, the latter with plants. The results are the production of new 
forms of plants and animals by external influence acting directly on 
the germ cells. This has been accomplished by exposing the cells to 
such influences as temperature, moisture, radium or chemicals. Let us 
take the work of McDougal. He has injected chemicals into the ovary 
of certain plants as Raimannia, Oenothera, Oereus and Pentstenon in 
such a way that both egg and sperm are brought into contact with 
them. This act often results in the destruction of the seed, often has 
no effect, but occasionally seeds are produced that grow into plants 
sharply distinguished from the parents. But the most interesting thing 
about these new forms is that they breed true and — though no further 
stimulus is used — do not revert to the original type. They are true 
mutations, the hereditary qualities have been changed by a direct act 
of man. These experiments are very new, their interest is as yet purely 
theoretical, but they may open possibilities whose practical importance 
can hardly be overestimated. 
The science of plant breeding has by no means reached a point where 
we can accept any one theory as final. The time is ripe for suspension 
of judgment. In 1874 Tyndall wrote of evolution, “The first step only 
towards experimental demonstration has been taken. Experiments now 
begun might a couple of centuries hence furnish data of incalculable 
value which ought to be supplied to the science of the future.’’ But a 
fraction of the time set by that optimistic radical has passed and we 
should resent any attempt to close debate thus early in our work. Varia- 
tion has been classified and it is certain that the classification will 
be of great practical importance, but we do not know whether these 
groups have even as great validity as the conception of independent 
species which served biology so long and so well. They may inter- 
